船用汽轮机组振动激励源特性分析

Analysis of Characteristics of Vibration Excitation Sources for a Marine Steam Turbine Set

船用汽轮机组运行时会产生较强的振动,易引发关键构件的疲劳破坏,而充分了解船用汽轮机组的振动激励源特性是减小其振动的前提。对某船用汽轮机组在不同运行工况下的振动激励源特性进行仿真研究。首先,分别通过理论分析和数值计算得到汽轮机组的旋转和气动激励源,计算不同运行工况下的等效激励力;然后,将等效激励力加载到地面安装条件下的汽轮机组有限元模型上,计算不同工况下汽轮机组的振动响应;最后,通过对比不同工况下汽轮机组的响应特征,确定旋转不平衡力是汽轮机组所受激励的主要成分,并进一步建立船用汽轮机组的振动加速度与机组转速的关系。该研究方法及有关结论对船用汽轮机组减振优化设计具有一定的指导意义。

During operation of the marine steam turbine set, excessive vibration can happen, which may lead to fatigue failures of important components. Therefore, fully understanding the characteristics of vibration excitation sources is a prerequisite for the vibration reduction of the marine steam turbine set. In this paper, a simulation study of a typical steam turbine set is performed and the vibration excitation sources are analyzed under various conditions. Firstly, through theoretical analysis and numerical simulation, the rotor-dynamic and aerodynamic vibration excitation sources are obtained.On the basis, the equivalent excitation forces are calculated. Then, the equivalent excitation forces are applied to a finite element model of the steam turbine set which is rigidly connected to the ground. And the vibration responses of the steam turbine set are calculated under different working conditions. Finally, by comparing the vibration responses, the unbalanced forces of rotation are found to be the dominant vibration excitation source. And the relationship between the vibration acceleration and the rotation speed of the turbine is derived by curve's fitting. This work provides a guideline for the vibration reduction of the marine steam turbine sets.