1000MW汽轮发电机组基础模型模态试验研究

Modal Test on the Model of a Foundation for 1000MW Turbo-unit

为评价实际工程中的1000MW汽轮发电机组基础的振动特性,本文采用模型模态试验方法进行研究.首先以该基础为原型基于相似原理制作1/10缩尺模型,并使用激振器空间激振方法对模型进行模态测试.然后采用LMS Test Lab系统进行模态分析,得到原型在0~70Hz范围内的各阶振型、自振频率、阻尼比,最后通过振动理论预测出原型强迫振动动力响应.试验结果表明,该基础整体振动的振型占主体地位,在机组工作转速范围内最大振动速度均方根值远小于3.8mm/s的限值,最大振动线位移中间平台部分测点超出0.20mm的限值,因而建议加强中间平台的振动控制.

The purpose of this study is to make an evaluation on the vibration characteristics of a foundation for 1000 MW turbo-unit in a real engineering,and the method adopted is modal test on the model.First,with the foundation as prototype,a 1/10-scaled RC model is constructed based on principle of similitude.Then a test of dynamic characteristics on the model is carried out in threedimensional space with exciters.Through modal analyzing by using LMS Test Lab system,results within the scope of 0~70 Hz of the prototype are acquired,including each mode shape,natural frequency and damping ratio of vibration.According to the theory of vibration,the dynamic response of forced vibration of the prototype is predicted.The results show that the type of overall vibration plays a dominating role in the foundation.And in the range of working speed,the maximum RMS of vibration velocity is much less than the limit value of 3.8 mm/s,and the maximum amplitude of vibration displacement is beyond limit value of 0.02 mm in part of measure points on the middle floor.Therefore,this paper proposes that vibration control of middle floor of the foundation should be reinforced.