大型转子-基础-土壤系统的动力分析

Dynamic Analysis of the Large Rotor-Foundation-Soil System

本文对大型汽轮发电机组-基础-土壤系统采用模态综合技术进行了动力分析.用弹性半空间理论建立土壤的模型,基础底板则通过弹性薄板的李兹(Ritz)函数近似解的形式来描述.用三维梁单元来建立基础底板以上的框架结构和转子系统的运动方程.此外,还用模态应变能的相对大小,在这种复杂机械结构系统存在的众多固有频率中,区分出哪些是属于主要为转子系统的固有频率,称为“重要振动固有频率”,以确定系统的临界转速.最后,对引进的一台500MW汽轮发电机组的动力特性进行了分析.

By utilizing the fixed-interface modal synthesis technique, the dynamic analysis of the large rotor-bearing-foundation-plate-soil system is presented in this paper. The model of soil is based on the elastic half-space theory. The approximate solution by Ritz Method of elastic thin plate is used to describe the mat of the foundation. The equations of motion of the other part of the foundation and the rotors are established by the model of three dimension beam elements. In this paper, the method of comparing the mode strain energy of every natural frequencies is used to distinguish the significant vibration frequencies of rotor system from the multitudinous natural frequencies of system and then the critical spin speed of system can be determined. Finally, the dynamic analysis of a 500. mw. turbogenerator system is carried out.