核电站半速汽轮机弹簧基础隔振效果评价方法的探讨

Evaluation Method for the Vibration Isolation Effect of the Spring Foundation for Half-Speed T/G Set in NPS

岭澳二期核电站的半速汽轮发电机(工作频率25Hz)采用了弹簧隔振基础,通常情况下,将弹簧基础简化为单自由度体系来计算的隔振效率,但用SAP2000有限元软件对岭澳弹簧基础隔振效率进行计算发现,有限元方法得到隔振效率与单自由度体系的结果差异较大,其原因在于单自由度体系计算方法无法考虑台板刚度对隔振效率的影响,因此采用单自由度体系的简化计算方法来计算汽机弹簧基础隔振效率是不合适的,对于汽轮机弹簧基础的评价方法建议如下:采用有限元的方法来计算各个弹簧支座处的传递系数,并采用SRSS组合方式来考虑多个扰力的影响,绘制机器工作频率一定范围内(如±25%)各个支座处传递系数-频率曲线,对弹簧基础隔振效率进行全面评价。

A spring foundation is used for the half-speed T-G set with 1500rpm operating speed in LingAo Phase, NPS project. Generally the vibration isolation efficiency of the spring foundation can be obtained to simplify a spring foundation to a single degree freedom（SDOF） system. The dynamic analysis of the spring foundation in LingAo project is performed by the program SAP2000 and the vibration the results are obviously different from those by the simplified isolation efficiency of every supports are obtained. But SDOF method. This simplified method is not suitable for calculating the vibration isolation efficiency of the spring foundation which can＇t take the influence of foundation stiffness into account. The recommendations about evaluating the isolation effect are as follows： the vibration isolation efficiency should be obtained by FEM, SRSS combination is used to consider the influence of several unbalance forces on the foundation, the basis for evaluating the Isolation effect is the curve of vibration isolation efficiency versus frequency within a certain frequency range such as 75% to 125% of the set service frequency.