不同基础形式对大型核电半速机组轴系动力特性的影响

摘要

为量化研究采用不同基础形式时汽轮发电机组轴系动力特性的差异,采用基础与轴承座均为动态支承刚度边界的方法,以某百万级核电半速机组为计算实例,计算得到常规固定基础及弹簧隔振基础下各轴承座的支承动刚度,并在2种支承边界下计算分析了轴系临界转速、轴颈不平衡响应及轴系对数衰减率等主要动力特性.结果表明:2种基础形式下,轴系各转子临界转速和轴颈的不平衡响应值均很接近,轴系失稳转速大于2 000 r/min,选用弹簧基础时轴系各转子水平向临界转速略有减小,而垂直向临界转速有所增大,通过优化设计可使弹簧基础的支承刚度具备与常规固定基础等效的支承刚度.%To quantitatively study the influence of foundation on dynamic characteristics of the shafting in turbine-generator set,numerical calculations were carried out to the support dynamic stiffness of different bearing seats for a 1 000 MW nuclear power half-speed unit,under conditions respectively with conventional foundation and spring foundation,by taking the foundation and bearing seat as the boundary of support dynamic stiffness,based on which an analysis was performed to the main dynamic characteristics,such as the critical speed of shafting,the unbalance response of journal and the logarithm decrement of shafting,etc.Results show that the critical speed of rotors and the unbalance response of journals are very close in value under above two foundation conditions,with both instability speeds of shafting greater than 2 000 r/min.The critical speed of rotor in horizontal mode declines and that in vertical mode rises,in the case spring foundation is adopted,under which condition the support stiffness can be optimized to a degree equivalent to conventional foundations via appropriate designs.