Coupled Analysis of the Shaft Vibration of the Simple Rotor System and the Rotor-Dynamic Fluid Forces in the Annular Plain Seal

Rotor dynamic (RD) fluid force generated in turbomachinery has significant influence on stability of the entire rotor system. Therefore, in order to improve system reliability, predicting RD fluid force from the initial design stage is important. In this study, a coupled analysis method of finite difference analysis of RD fluid force acting on an annular plain seal and shaft vibration analysis of simple rotor system is constructed. In this analysis method, both calculations of fluid force and shaft motion are performed at the same time considering the interaction between them. Using the constructed coupled analysis method, the behavior and stability of the rotor system in the case of large whirl amplitude where the nonlinearity of fluid force becomes prominent are investigated. Moreover, domain of entrainment of stable equilibrium position is focused, and the influence of pre-swirl ratio on this domain is investigated