基于旋转软化的汽轮发电机组轴系振动研究

利用有限元法建立了汽轮发电机组轴系试验台模型,分析了陀螺力矩、应力刚化及旋转软化效应对弯曲和扭振模态的影响,导出了相应的动力学方程,运用程序计算了该轴系试验台模型的扭转、弯曲及弯扭耦合振动.结果表明：扭转振动影响到轴系的安全运行,存在多种形式的弯扭耦合振动;旋转软化效应对第一、第二阶弯曲反进动模态产生显著影响;应力刚化效应进一步提高了第三阶弯曲正进动模态频率;考虑应力刚化及旋转软化效应的影响,可求得扭振模态频率及临界转速;与梁模型相比,采用实体单元时的仿真度高,计算结果更准确.

Study on Vibration of Turbo-Generator Shaft System Based on Spin Softening

A turbo-generator shaft model was established using finite element method,with which the effects of gyroscopic moment,stress stiffening and spin softening on lateral-torsional vibration mode of the shaft system were analyzed,and subsequently corresponding dynamic equations were deduced,while the torsional,lateral and coupled lateral-torsional vibration calculated with computer programs.Results show that the torsional vibration has a certain influence on safe operation of the system; there are several forms of coupled lateral-torsional vibration; the spin softening has significant influence on the first and second backward whirl mode; the stress stiffening further increases the frequency of the third forward whirl mode; the torsional vibration frequency and critical speed can be obtained in consideration of both the effects of stress stiffening and spin softening.In comparison with beam model,the solid element model has higher simulation degrees,resulting in more accurate calculation results.