摘要
迷宫密封在叶轮机械中使用广泛,且对转子系统稳定性有很大影响,但是很少有文献关注轴颈偏心与迷宫密封和系统稳定性之间的关系。课题组提出一种基于FLUENT软件的转子密封耦合系统的瞬态仿真方法,在每个时间步,首先求解纳维斯托克斯方程获得轴颈表面的瞬态气体密封力;接着,求解单圆盘转子密封系统的有限元模型,计算轴颈在下一个时间步的位移;在每个时间步中,将计算得的气体密封力和轴颈位移进行数据交换。此外,该方法使用的动网格技术可在轴颈任意运动状况下保证网格质量。从计算结果可以看出,当偏心到达一定位置时出现了半频振动,这意味着轴颈和密封之间的相对位置对转子密封耦合系统的稳定性有极大影响。为分析转子密封耦合系统的瞬态特性,瞬态泄漏量变化、周向和轴向压力分布等计算结果也在文中给出。在一台装有位置可调迷宫式密封的汽轮机上进行实验,结果显示改变轴颈与密封间相对位置后振幅显著降低,稳定性提高,验证了计算结论的正确性。
Labyrinth seals are widely used in turbomachinery and play an important role in the stability of the rotor bearing system. But few literatures focus on the relationship between the journal offset in labyrinth seals and the system stability. A transit simulation method based on FLUENT software was introduced to model the coupled rotor-seal system.The method which involved a dynamic mesh method similar in journal bearing calculation could ensure fine mesh quality during the arbitrary motion of the journal. In each time step,the Navier-Stokes equations were solved to obtain the transient fluid seal force on the journal surface. With the obtained fluid seal force,the FEM model of a single disc rotorseal system was numerically solved to predict the displacement of the journal in the next step. During each transient time step,the computed fluid seal force and the rotor motion displacement were transferred to each other timely. The axis orbits under different offsets show that half-frequency vibration can be seen in some positions,which means the relative position between the journal and the labyrinth seals can greatly affect the stability in the coupled rotor-seal system. Other results like transit leakage change,the circumferential and axial pressure distribution are also given to show the transit characteristics of the coupled rotor-seal system. The experiment is carried out in a steam turbine with a position adjustable labyrinth seal. The experimental result shows that the amplitude of the vibration decreases after the change of the relative position between the journal and the labyrinth seals which validates the conclusion of the calculation.
出处
《轻工机械》
CAS
2017年第6期32-36,共5页
Light Industry Machinery
基金
国家重点研发计划项目:危险化学品储存设施燃爆毁伤效应及事故调查技术(2016YFC0801204)
