多级失谐长叶片轮盘-轴系强耦合振动机理及动力特性研究

Coal-fired ultra-supercritical steam turbines and nuclear power steam turbines are developing towards high efficiency and large power, and the last stage blades become longer, shafts become more complex. The overall vibration characteristics of bladed disk-shaft coupling system are different from components. Therefore, the traditional method for calculating the vibration of blade and shaft separately is not applicable any more. The aim of the project is to reveal strong coupled vibration mechanism of multi-stage tuned/mistuned bladed disk-shaft systems, and develop an effective method for calculating the dynamic characteristics. Firstly, considering stiffness nonlinear caused by rotation, a three-dimensional algorithm of high efficiency and fidelity is developed to calculate modes and dynamic response of multi-stage tuned/mistuned bladed disk-shaft systems. Based on modes of single component, a quasi-modal synthesis method is proposed, which has high engineering application value and high efficiency for predicting modes of the multi-bladed disk-shaft system. Secondly, the influence factor of dynamic characteristic of the coupling system is studied, a perturbation component modal synthesis method for calculating coupling mode is proposed. The optimal arrangement patterns of mistuned blades will be given to minimizing system response due to electrical interference. Finally, the mechanism of the coupled vibration between blade bending and shaft torsion, and multi-stage bladed-disk will be revealed from both theory and experiment. The research will provide theoretical basis for the design of rotor and blade of large power steam turbines.

燃煤超超临界汽轮机和核电汽轮机向高效率、大功率方向发展已成趋势，末级叶片更长，轴系更复杂，导致机组长叶片轮盘-轴系耦合系统整体振动特性有别于单个部件，因此传统上将叶片和轴系振动独立分析的方法已不再适用。本项目考虑叶片谐调和失谐情况，重点研究多级长叶片轮盘-轴系强耦合振动机理和动力特性的高效预测算法。首先，考虑旋转引起的刚度非线性，发展一种三维的多级叶片轮盘-轴系耦合振动模态和动态响应的高效、高保真算法；基于部件独立设计时的模态结果，发展一种具有工程应用价值的高效计算多级叶盘-轴系耦合系统模态的准模态综合法。然后，研究影响耦合系统动力特性的关键因素，以电气干扰下系统响应最小为目标，提出自然失谐叶片的最优排布方式。最后，从理论和试验两个层面，揭示叶片轮盘弯曲和轴系扭转振动的耦合机理，以及多级叶片轮盘间振动的传递规律，寻找出现强耦合的条件，为新型、大功率汽轮机长叶片和轴系设计提供理论依据。

超超临界汽轮机和核电汽轮机向高效率、大功率方向发展已成趋势，末级叶片更长，轴系更复杂，导致长叶片轮盘-轴系耦合系统整体振动特性有别于单个部件，传统上将叶片和轴系振动独立分析的方法已不再适用。为此本项目开展了多级失谐长叶片轮盘-轴系强耦合振动机理及动力特性研究。.发展了一种三维多级叶片轮盘-轴系耦合振动模态和动态响应分析的高效、高保真算法；基于部件独立设计时的模态分析结果，提出了一种具有工程应用价值的高效计算多级叶盘-轴系耦合系统模态的准模态综合法。.建立了成圈长叶片零节径伞形弯曲和轴扭转耦合振动分析的等效动力学模型，掌握了影响耦合振动的关键因素，给出了产生强耦合的条件，揭示了叶片分支振动引起的三种类型耦合振动模态频率和叶片伞形振动频率的关系。.综合模态综合法和摄动法优点，提出了多级失谐叶片轮盘-轴系耦合振动分析的摄动降阶算法；针对高转速下叶盘系统受到科氏力，发展了一种考虑科氏效应的高速失谐叶盘振动分析的高效降阶算法。分析了科氏效应、排布方式及盘-轴耦合效应等因素对失谐叶盘结构振动响应局部化的影响，优化了失谐叶片轮盘-轴整体系统的动力特性。.计算了某660MW汽轮发电机组叶片-轮盘-转子耦合振动系统的固有频率和模态振型，结果表明，考虑末叶和次末叶实际结构的轴系扭转振动计算结果比不考虑末叶和次末叶实际结构的轴系振动计算结果多出了11个耦合分支振动模态。发现存在叶片零节径第1阶振动和轴系的耦合，以及叶片零节径第2阶振动和轴系的耦合。同样，分析了某1000MW汽轮发电机组叶片-轮盘-转子耦合振动系统的固有频率和模态振型。研究表明，不考虑耦合作用，将威胁转子的安全运行。.研究了旋转状态下轴系扭转和长叶片切向振动耦合振动测试方法，和企业一起对某600MW机组叶片轮盘-转子系统开展了耦合振动试验，验证了分析模型的正确性。.本研究可为新型、大功率汽轮发电机组转子系统的设计提供理论支撑。