Bidirectional Effects of Acceleration on Rotor–SFD System: Dynamic Analysis Based on Imbalance Condition Differences

The rotor is a crucial component in rotating machinery, where its stability directly impacts performance and safety. Imbalance-induced vibrations can cause severe component wear, resonance instability, and even catastrophic failures, especially in high-speed systems like aero-engines. While the squeeze film damper (SFD) is widely used for vibration suppression, the effects of imbalance (manifested as SFD eccentricity) on its dynamic performance are not well understood. Additionally, the combined impact of imbalance and acceleration on rotor–SFD system stability has not been systematically investigated. This study uses numerical simulations to explore the influence of SFD eccentricity, caused by imbalance, on its dynamic characteristics. Experimental tests are conducted to examine the effects of imbalance and acceleration on rotor–SFD dynamics. Results show that increasing imbalance raises SFD eccentricity, reducing the effective oil film bearing area. This results in a rapid increase in the oil film’s stiffness and slower growth in damping, enhancing nonlinearity and reducing stability. Under small imbalance conditions, increasing acceleration improves stability by facilitating critical speed crossing and reducing vibration amplitude. However, excessive imbalance renders acceleration control ineffective, exacerbating system instability. This study provides valuable insights into the interaction between imbalance, acceleration, and SFD performance, offering guidance for optimizing rotor–SFD system parameters and ensuring stable operation.