核电主泵失电惰转时推力轴承动态特性分析

Analysis of Dynamic Characteristics of Thrust Bearing for Nuclear Power Plant RCP during Loss of Power Coastdown

分析了核电主泵冷、热态工况下失电惰转时推力轴承的动态特性。首先推导了转子轴向力的变化关系式,并基于雷诺润滑理论对推力轴承进行了数学建模,采用有限差分法进行数值计算并编制了计算程序。利用程序对主泵推力轴承若干设计工况进行了验算,结果与设计预期相符。随后利用计算程序分别对冷、热态工况下主泵失电惰转时推力轴承的动态特性进行了模拟,结果表明:热态工况下主泵惰转至低转速时推力轴承最小油膜厚度低于经验安全值,且最高温度迅速上升,对主泵惰转不利;冷态工况下惰转预计是安全的。

The dynamic characteristics of the thrust bearing for one nuclear power plant reactor coolant pump(RCP) during loss of power coastdown has been simulated and analyzed. Firstly the axial force of the RCP rotor has been derived. Then a mathematical model for the thrust bearing has been established based on Reynolds lubrication theory, afterwards the model is numerically solved by finite difference method and a calculation code is programed. The code is then validated through the calculation and comparison with some design operation conditions of the RCP thrust bearing. The dynamic characteristics of the thrust bearing during loss of power coastdown under hot and cold condition is simulated and calculated separately, and the calculation results suggest that when the RCP being coastdown to low speed under hot condition, the minimum oil film thickness of the thrust bearing will be less than the empirically safe margin and the maximum temperature increases sharply, which is adverse to the safe operation of the RCP. Meanwhile coastdown in cold condition is predicted to be safe.