水轮发电机组主轴系统的水流激励特性

Hydraulic excitation exerting on main shaft system of hydraulic turbine-generator units

以混流式水轮发电机组主轴系统为研究对象,应用有限单元法建立包含电磁参数、结构参数和水力参数的混流式水轮发电机组主轴系统全局耦合动力学模型.在此动力学模型基础上,针对水轮发电机组主轴系统转轮处存在横振和扭振的情形,推导通过转轮叶片这一中间传递元件作用在混流式水轮发电机组主轴系统上的水流激励,揭示混流式水轮发电机组主轴系统的振动特性与水流激励之间的内在关系.结果表明:水流激励通过转轮叶片这一中间传递元件作用在主轴系统上,是造成水轮机主轴系统激烈振动的主要原因之一;水流激励不仅与转轮内复杂压力脉动及主轴系统的结构参数有关,而且还与主轴系统的振动特性有关;水流激励和主轴系统的振动相互作用、相互影响,从而使混流式水轮发电机组主轴系统产生流固耦合振动现象.最后通过实例讨论水流激励对混流式水轮发电机组主轴系统动态特性的影响.

By the finite element methods（FEM）,the global coupling dynamic model of the main shaft system of a Francis turbine-generator unit is established,which includes electromagnetic parameters,structural parameters and fluid parameters.Based on the existence of transverse vibration and torsional vibration of the turbine shaft system,the hydraulic excitation exerting on the main shaft system,which is translated by the blades,is derived.According to the dynamic equations of the main shaft system,the internal relations between the hydraulic excitation and the vibration characteristics of the main shaft system are discovered.The studies show that the hydraulic excitation can be transfered by the turbine blades as middle transform components to exert on the main shaft system,and that the hydraulic excitation is not only related to the complicated pressure fluctuation in turbine runner,but also to the structural parameters and the vibration of the main shaft system,and that the hydraulic excitation and the vibration of the main shaft affect with each other.The fluid-solid coupling vibration of the main shaft system of the Francis turbine-generator unit may take place subjected to the hydraulic excitation.An example is presented at last.