导轴承系统对水电机组轴系特性影响分析

导轴承特性是影响水轮发电机组轴系振动特性和稳定性的根本因素。导轴承的特性取决于轴承的几何参数及边界条件。为了研究不同轴承几何参数及边界条件对机组轴系特性的影响,本文采用单变量参数分析法,通过分别改变轴承瓦块数,瓦间隙、轴瓦包角、油膜温度参数,运用临界转速和对数衰减率对轴系特性进行分析研究,得到轴承系统对轴系特性的影响规律。结果显示:随着瓦块数和包角的增加及油膜温度的降低,轴承的偏心率逐渐减小,油膜最小厚度逐渐增大,但随着半径间隙的增大,轴承偏心率和油膜厚度均增大。其中随着轴承参数的变化,一阶临界转速和对数衰减率变化很小,二阶临界转速呈现不同的变化趋势。最终为以后的轴承选择或运行提供一定的参考依据。

Analysis on impact of guide bearing system on characteristics of hydro turbine shaft system

Characteristics of guide bearing are fundamental factors of the vibration characteristics and stability of turbine generator shafts. The properties of guide bearing depend on its geometric parameters and boundary conditions. This paper examines and analyzes the vibration behaviors of a turbine unit shaft to study the influence of different geometric parameters and boundary conditions of the bearing on the characteristics of the shaft, by using the method of single variable parameters and changing the number of bearing tiles, tile clearance, tile angle, and oil film temperature. We obtained the influence trend of guide bearing on the shaft system characteristics via an analysis of the shaft behaviors in terms of critical speed and logarithmic decrement rate. Results show that with the increase in the number of bearing tiles and tile angle or the decrease in oil film temperature, bearing eccentricity gradually decreases and minimum oil film thickness increases gradually, while with the increase in radius clearance, both bearing eccentricity and oil film thickness are increased. Also with the changes in the geometric parameters of the shaft, the first-order critical speed and the logarithmic decrement rate change little, but the second-order critical speed presents a different trend.