基于'流体-结构'耦合的主油泵转子动态响应分析

摘要

Main oil pump(MOP)is one of the most important equipments for a steam turbine unit.In order to ensure safety.the mechanical design of an MOP is performed according to the static and dynamic characteristics of the rotor,which is usually estimated by a simplified computational model.Nevertheless,the rotor has complex boundary conditions that are difficult to be included in the compfitational model.One of these boundary conditions is the high oil pressure distribution on the impeller,which can considerably modify the natural frequencies of the rotor and meanwhile affects stress and deformation of the rotor.In order to analyze this effect on a MOP rotor of 1000MW steam turbine more accurately,a numerical simulation was carried out using the approach of FSI analysis.The rotor was numerically simulated and the static structural and rotor dynamic response analysis were conducted both in air and in oil.It also shows that the mode shapes in oil are similar to those in air.and the presence of oil reduces the natural frequencies considerably while the damping increases.The approach used in this investigation is proved to be valid,so that it can be extended to the study of the static and dynamic behavior of any other pump rotor with similar geometrical characteristics.%在主油泵的结构设计中,必须从安全的角度考虑转子的静力学和动力学特性限制,并且会采用简化的计算模型来分析这些特性.然而主油泵转子有一些复杂边界条件难以包括在简化模型中,作用在叶轮表面上的油压分布就是其中之一.这不仅会改变运行中转子的固有频率,而且影响转子的应力和变形.为了更精确地分析这些影响,本文采用"流体一结构"耦合法对1000MW汽轮机组润滑油系统主油泵的流场和结构力学性能进行数值模拟,对分别工作在空气和油中的叶轮进行转子静力学和动态响应特性分析.结果表明,在空气和油中该转子的振型类似,在油中随着阻尼增加其固有频率相应的减小,与实际情况一致.本文的研究结果证明所提出的方法是有效的,对类似几何特征的其它泵转子的动态特性分析具有借鉴作用.