中文摘要：

于立式布置的混流式水轮发电机组,由于横向振动的固有频率往往高于激振力的频率范围,转子轴承系统的动态特性需要特别关注,而系统的刚度及质量矩阵求解难度较大,所以用解析法求解水轮机主轴系统的临界转速比较繁琐。利用虚拟样机技术,以某电站水轮发电机组为例,通过建立水轮发电机组主轴系统的虚拟样机模型,快速计算了主轴系统的临界转速,分析了轴承刚度和阻尼对临界转速的影响。仿真得出结论：通过改变导轴承支撑刚度可以改变临界转速,轴承与主轴系统的动态性能指标是相互制约的,因此在高速旋转机械动力学设计时,轴承与转子设计必须一起协调进行,轴承刚度的动态特性不容忽略。

英文摘要：

Natural frequency of lateral vibration is outside the excited force＇s frequency range for the vertical hydraulic generator unit,so it＇s very necessary to know well the character of dynamic of the rotor-bearing system.It is difficulty to calculate for the mass matrix and the stiffness matrix,therefore critical speed is very complicated calculate based on analytic method.For the practical unit,the Virtual Prototyping of hydroelectric machines model of shaft system is created.The connection between the critical speed and the bearing＇s stiffness and damping is analyzed.The simulation results indicate that it is feasible to gain critical speed and the critical speed can be changed by modify guide bearing＇s stiffness.The character of dynamic between the rotor system and the bearing is mutual condition.As a result,it is necessary to devote much attention to the character of dynamic of bearing in dynamics design of high-speed machinery.