轴承/密封耦合作用下流体激振特性研究

Research on Fluid-induced Vibration Characteristics under Coupling Effect of Bearings and Seals

以转子—轴承—密封系统为对象,建立轴承/密封耦合作用对系统动力特性影响的有限元模型。分别应用有限差分和CFD方法对轴承、密封动力特性系数进行求解。理论研究表明密封对转子不平衡响应的影响主要集中在共振区域。通过在密封入口引入负预旋可以提高系统的稳定性,密封气流力对系统稳定性影响随转速的升高也越来越大。通过选择合适的轴承型式可以补偿密封气流力对系统稳定性带来的不利影响。试验发现随着转速增加,试验转子在5 000 r/min附近时开始出现比较明显的半频分量,而且随着转速继续增加,半频分量的幅值变大。密封流体激振力的存在促进轴承内油膜失稳故障发生,影响系统稳定性。

Finite element model of a rotor-bearing-seal system was set up to study the influence of the coupling effect of bearings and seals on the system characteristics. Finite difference method and CFD method were employed to obtain the dynamic coefficients of the bearings and seals. Theoretical studies show that the seal has a large influence on the synchronous response of the rotor in the resonant region. Negative preswirl at the inlet of the seal tends to improve the system stability. Influence of the seal force on the system stability becomes more and more serious with the increasing of the rotating speed. Results also show that the detrimental influence of the seal can be compensated by using suitable bearings.Test results show that the subsynchronous vibration appears at about 5 000 r/min, and it becomes larger and larger with the increasing of the rotating speed. The existence of the seal force tends to promote the occurrence of instability faults in bearings and affect the system stability.