汽轮机转子动力特性的多因素分析及稳定性预测

Study On the Multi-factors Influence on Rotor Dynamic Characteristics and Stability Prediction

针对汽流激振对汽轮机转子动力特性和稳定性的影响,文中应用动网格建立三维转子涡动模型,通过正交试验完成汽流激振下转子动力特性的多因素分析,得到影响动力系数的显著因素。利用频率涡动比和有效阻尼研究了显著因素对转子稳定性的影响规律。结果表明：涡动转子表面压力波动剧烈,汽流激振力呈非线性变化;涡动速度、自转速度、涡动半径、压比以及交互作用对转子动力特性均有一定的影响,其中涡动半径、涡动速度和压比对转子动力系数有较大的影响,而自转速度的影响较小;当涡动速度在1500~3000r/min之间,转子失稳的可能性增加。若涡动半径增加,控制涡动速度会抑制大幅低周涡动,可避免转子失稳。

According to the influence of steam flow excited vibration on rotor dynamic characteristics and stability, the significant factors affecting the dynamic coefficients can be obtained in multi-factors analysis of rotordynamic characteristics which influenced by steam flow excited vibration through the orthogonal experiment, and the three-dimensional whirling rotor model was established via using mesh deformation. On this basis, the influence of the significant factors on the rotor stability was studied by using the whirl frequency ratio and the effective damping. The results show that the pressure fluctuation of whirling rotor surface is intense, and the steam exciting force has nonlinear change. Whirling velocity, rotation velocity, whirling radius, pressure ratio and the interaction have certain influence on the rotor dynamic characteristics, among which the whirling radius, whirling velocity and pressure ratio have more influence on the rotor dynamic coefficients, while the influence of rotation velocity is less. The possibility of rotor instability increases when the whirling velocity is between 1500-3000 r/min. However, the rotor instability can be avoided by controling whirling velocity when the whirling radius increases, for it will suppress the large amplitude low cycle whirling motion.