核电站百万千瓦级半速汽轮发电机组弹簧隔振基础强迫振动模型试验探讨

A Study on Forced Vibration Model Test of Spring Supported Foundation Half Speed 1000MW T/G at Nuclear Power Plant

对汽轮发电机组弹簧隔振基础进行模型试验的最根本理论是相似理论,最关键的技术是模态分析。本文利用相似理论与模态分析的传递函数矩阵方程,推导了强迫振动模型试验的相似准则方程,确定了r阶模态的决定性相似准则为r阶阻尼比Dr与r阶调谐比ηr,非决定性相似准则为振动线位移组合量。对百万千瓦级半速核电站汽轮发电机组弹簧隔振基础的强迫振动进行模型试验时,各阶模态的阻尼比与调谐比必须相等,但是模型与原型的各阶阻尼比是否能够做到相等,缺乏验证。而且目前阻尼比取值不太合理,模型试验没有给出有益的建议。振动系统包括汽轮发电机组、基础台座、弹簧隔振器与阻尼器等,模型试验在机器的激振频率、激振力强度与分布等方面难于满足相似理论。模型试验在满足弹簧隔振器的刚度、压缩量与系统频率要求时也有困难。

The basis theory and the key method for the model test of the spring supported T/G foundation is the similarity one and the modal analysis.A similar criteria equation is deducted for the forced vibration model test of the spring supported T/G foundation with the similar theory and from the transmission function matrix equation in this paper.Two determinant criteria for r order of vibration modal are r order of the damping ratio Dr and the tuning ratio ηr.An indeterminate criterion is a compound of the r order of the displacement,the excitation and the spring rate.As a result,each order of the damping ratio and the tuning ratio for the model must be equal to those for the prototype during the model test,but which is still not proved.Currently,the damping ratio given by the national codes is not very reasonable,and the model tests finished in the past did not give us any valuable suggestion.The vibration system is composed of the T/G set,the foundation block,the spring elements and the dampers.The model test is difficult to be similar to the exciting frequency,excitations and the acting points of T/G set on the foundation block.The similarity is also difficult to be followed in the stiffness and the compression of the spring elements and the system natural frequency.