【摘要】 AP1000三菱核电半速汽轮发电机组采用弹簧基础后,会不会影响机组的轴系临界转速?这是汽轮机工程师希望回答的一个关键问题.在计算机组轴系临界转速时,轴系支承刚度是轴承油膜刚度(包括轴承座刚度)与基础支承刚度的串联和.对固定基础,往往会给人基础的支承刚度为无穷大的感觉.其实这个概念不确切,因为振动是动态问题,牵涉到固有频率(特征值)与模态振型(特征向量)等动态概念,不能用静态概念解决.确切的概念应该用基础的动刚度,而不是静刚度,所以固定基础的支承刚度并不是无穷大.为此,在对弹簧基础进行优化设计后,进行了10～50Hz范围内AP1000三菱机组固定基础与弹簧基础的动刚度的对比计算分析.计算结果表明,弹簧基础与固定基础的动刚度都是有限值,频域曲线相互交错,数量级相同,最小值都容易做到大于2×106kN/m,符合Siemens与Alstom公司的要求.由此可以期望弹簧基础基本不会改变机组的轴系临界转速.另外,介绍怎样对弹簧基础进行优化设计,使其动刚度在10～50Hz频域范围内都大于2×106kN/m.更多还原

【Abstract】 If a spring foundation is used for AP1000Mitsubishi nuclear half speed turbo-generator(T/G) set,a key question needs to be answered for turbine engineers:if the critical speed of the shaft system of the T/G set will be highly changed?Sum of the stiffness in series by oil film’s,including the pedestal’s,and the foundation’s is used to calculate the critical speed.Infinity seems to be usually taken as the stiffness for the conventional foundation.It is incorrect,because vibration,including eigenvalues and eigenvectors,can only be resolved dynamically,not statically;so that a dynamic stiffness,not static one should be used as the foundation one.A comparative analysis of the dynamic stiffness in the area within 10～50Hz for both the conventional one and an optimized spring one is performed.The result shows that the dynamic stiffness for both foundations is of a limited value with the same in order of magnitude,intersected within10～50Hz and the minimum easily to be higher than 2×106kN/m.It is requested by Siemens and Alstom to ensure not to change the critical speed,when the foundation is changed from a conventional to spring one.In addition,how to optimize the spring foundation to ensure the minimum dynamic stiffness for the spring foundation to be higher than 2×106kN/m will be introduced in the paper.更多还原