Lubrication analysis of low-speed and heavy-load journal bearing in wind turbine gearbox under different operating conditions

低速重载风电齿轮箱径向滑动轴承多运行状态润滑性能分析

School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, China

Received: 25 November 2022

Abstract

Aiming at the working conditions of frequent starting, low speed and heavy load, and yaw tilting of radial sliding bearings in wind turbine gearboxes, a numerical analysis model of the lubrication performance coupled with instantaneous starting and operating conditions of radial sliding bearings was established based on the average Reynolds equation, and the start-up phase was analyzed. The motion trajectory of the shaft diameter and the axis center was used to obtain the change state of the bearing film thickness from the start-up to the stable stage; the influences of the comprehensive surface roughness, the journal inclination angle, and the journal rotation speed on the lubrication performance of the bearing during the whole stage of start-up and stable operation were studied respectively. The results show that the eccentricity has a maximum value in the starting stage, and the risk of film rupture caused by rough contact is the greatest. With the increase of the comprehensive surface roughness, the bearing capacity and friction coefficient both increase, and the maximum bearing capacity and friction coefficient in the starting stage are higher than those in the stable stage, which increase by about 13.62% and 131.58% respectively. With the increase of the inclination angle of the shaft diameter, the bearing capacity and friction coefficient both increase, and the maximum load capacity and friction coefficient in the starting stage are about 30% and 116% higher than those in the stable stage on average. With the increase of the speed, the bearing capacity of the bearing increases and the friction coefficient decreases, which is beneficial to improve the bearing performance. The calculation results provide an important basis for evaluating the wear risk of sliding bearings under frequent starting conditions, and provide a reference for the structural design and selection of sliding bearings, operating temperature, oil film pressure, etc.

摘要

针对风电齿轮箱中径向滑动轴承频繁启动、低速重载、偏航倾斜等工况, 基于平均Reynolds方程建立径向滑动轴承瞬时启动与运行工况耦合的润滑性能数值分析模型, 分析了启动阶段轴径轴心运动轨迹, 获得启动至稳定阶段轴承膜厚变化状态; 分别研究了表面综合粗糙度、轴颈倾斜角度、轴颈转速对轴承启动和稳定运行整个阶段润滑性能的影响规律。结果表明: 启动阶段偏心率出现最大值, 粗糙接触引起破膜风险最大; 随着表面综合粗糙度由0.6增大至1.2 μm, 轴承承载力和摩擦因数均增加, 启动阶段的最大承载力和摩擦因数比稳定阶段增加约13.62%和131.58%;随着轴径倾斜角度由0.000 1°增大至0.000 4°, 轴承承载力和摩擦因数均增大, 且启动阶段的最大承载力和摩擦因数比稳定阶段平均约高出30%和116%;随着转速的增加, 轴承的承载力增大, 摩擦因数减小, 有利于提高轴承性能。计算结果为评价滑动轴承频繁启动工况下的磨损风险提供了重要依据, 为滑动轴承的运行温度、油膜压力等轴承结构设计和选型提供参考。