汽流激振下汽轮机各向异性转子振动特性分析

Vibration Characteristics Analysis of Steam Turbine Anisotropic Rotor Under Steam Flow Excited Vibration

为了探究汽流激振对汽轮机转子振动特性的影响,通过数值模拟得到前8级不同负荷下汽流激振力,将其等效为气体轴承施加在转子上。用集总参数法模化某1000MW超超临界汽轮机高压缸转子,建立各向异性支承模型,利用Riccati传递矩阵法求解得到汽流激振对转子振动特性的影响。结果表明:在汽流激振作用区域,负荷越大,椭圆轨迹方位角越大。随着负荷增加,一阶固有转速增加,二阶减小,汽流激振力对固有转速影响不大。随着负荷变大,一阶和二阶的对数衰减率皆减小。当达到额定负荷时,对数衰减率为0.012,较无汽流激振力的下降97.5%,转子稳定性裕度严重不足,容易失稳。

Steam flow exciting force of the first eight stages under different loads was obtained through numerical simulation,which was equivalent to gas bearing applied to the rotor to explore the influence of steam flow excited vibration on vibration characteristics of a steam turbine rotor.The high pressure cylinder rotor of a 1000MW ultra-supercritical steam turbine was modeled by the lumped parameter method,and the anisotropic support model was established.The influence of steam flow excited vibration on rotor vibration characteristics was obtained by using Riccati transfer matrix method.The results show that when the load is greater,the azimuth angle of ellipse trajectory is greater.With the increasing of load,the first-order natural speed increases and the second-order decreases.Steam flow exciting force has little effect on the natural speed.As the load increases,the first and second-order logarithmic decrement rates decrease.When the rated load is reached,the logarithmic decrement rate is 0.012,which is 97.5%lower than that without steam flow exciting force,and the rotor stability margin is seriously insufficient,and it is easy to lose stability.