两种转子轴承系统模型的油膜失稳故障仿真

Oil-film instability fault simulation on two rotor-bearing system models

以单跨双盘转子系统为研究对象,针对滑动轴承在高转速时容易出现的油膜失稳问题,分别建立了考虑陀螺影响的转子系统集中质量和有限元模型,系统中含油石墨轴承和滑动轴承分别采用弹簧-阻尼模型和短轴承非线性油膜力模型,通过三维谱图、轴心轨迹和频谱图,对比分析了两种不同数学模型在不同载荷工况下(两圆盘偏心率同向和反向)的油膜失稳规律及系统复杂非线性动力学特性.两种数学模型的仿真结果均表明:油膜失稳会激起复杂的转频和失稳频率的组合频率成分,反向偏心比同向偏心提高了失稳转速,且在较高转速时能激起系统第2阶油膜振荡,并激发与前2阶油膜振荡频率有关的组合频率成分,二者的差异在于有限元模型的失稳转速略低于集中质量模型.研究结果可为转子油膜失稳故障机理及故障诊断提供依据.

Pertaining to the single-span double-disc rotor systems, the oil-film instability problem of highspeed sliding bearing often occurs. By considering the lumped mass of rotor systems with gyroscopic coupling effect, the lumped mass and finite element models are established. In details, the graphite selflubricating bearing and the sliding bearing are treated as the spring-damping model and the short- bearing non-linear oil-film force model, respectively. By the 3D spectral diagram, axle-center track and frequency spectral diagram, the oil-film instability rules and complicated non-linear dynamic properties of bespoke models are analyzed and compared under different working conditions, e. g. the same and reverse eccentricities of two discs. Accordingly, it is found from simulation results that the oil-film instability can excite the complicated combination of rotary and instability frequencies. Compared with the same eccentricity, the reverse eccentricity will accelerate the instability speed. In addition, the second-order oilfilm oscillation, along with the combined frequency components regarding the first two orders oil-film oscillation, is excited by higher rotary speeds. Moreover, the instability rotary speed from the finite element model is slightly lower than that from the lumped mass model. Therefore, this approach provides a reference to rotor oil-film instability mechanism and fault diagnosis.