考虑气流激振下汽轮机转子系统碰摩动力学特性研究

减小密封间隙是提高透平机械工作效率的一条重要途径，但同时也会因工作间隙减小而使动静结构件之间发生碰摩故障，为此针对某实际发生碰摩故障的汽轮机转子系统构建了有限元分析模型。在考虑气流激振作用的同时，通过对系统在不同位置发生碰摩时的动力学特性进行数值模拟分析，研究不同碰摩点处发生局部碰摩时轴承处的振动特征。分析结果表明：两支撑轴承处的轴心轨迹、频谱图等特征图呈现出一定的规律，系统主要为同频周期运动，但频谱中会出现高频成分；随着碰摩点靠近轴承或转子系统中心，系统的运动越来越复杂，出现了8字形和椭圆等轨迹，时域波形图中出现了削波现象；不同位置碰摩振动现象不同，可根据轴承处的响应特征图估计出碰摩故障发生的位置。

The dynamic behavior of the rotor system of a steam turbine subjected to rub-impact and fluid excitation at different locations

Reducing the clearance between stationary and rotating parts is an important way to improve the efficiency of turbomachinery, although this can make the machine prone to rotor-stator rub-impact. This paper sets up a theoretical model which first considers the stator misalignment. Then, combining an industrial steam turbine with annoying rub-impact faults and the finite element method (FEM), the dynamic characteristics of the machine under rub-impact at different locations are investigated. Fluid excitation effects are also considered. The numerical results indicate that the multi-vibration phenomena caused by rub-impact make the main contribution at the different rub-impact locations. The shaft center orbit and fast Fourier transform (FFT)(characteristics at the bearing locations) are subject to definite rules. The major vibration is synchronous, accompanied by some supersynchronous vibration when the rub-impact location is close to one of the bearings. As the rub-impact moves to the center of the rotor, the vibration characteristics at the bearing become more and more complex. The shaft center orbit may be an "8" or lemon shape. In addition, subsynchronous vibrations will emerge. There are some clipped phenomena in the time history wave. This work provides new insights into the variety of vibration phenomena exhibited by rotor-stator rub-impact and can help in diagnosing the location of rub-impact.