Dynamic Characteristics Analysis of a Large Wind Turbine Gearbox Supported by Journal Bearings Under Different Lubrication States

ABSTRACT

Due to their superior load density, planetary gear journal bearings (PGJB) are progressively replacing rolling element bearings in wind turbine gearboxes; therefore, accurately revealing the dynamic characteristics of drivetrains supported by these bearings under variable operating conditions is crucial for ensuring operational reliability. However, the nonlinear mechanism governing the influence of lubrication state transitions on system vibration response remains unclear. To address this, this paper establishes a flexible–rigid coupled dynamic model of a high‐power wind turbine drivetrain (WTD), aimed at investigating the coupling mechanism between lubrication state evolution and system vibration characteristics. A unified nonlinear force formulation integrating asperity contact and hydrodynamic oil film forces (OFF) is proposed, enabling the continuous simulation of the entire evolution process across boundary, mixed, and hydrodynamic lubrication regimes. The model is validated using field measurement data from an 8 MW wind turbine gearbox. The results indicate that the lubrication state dictates the system's spectral signature: Boundary lubrication induces strong high‐order nonlinear harmonics and modulation sidebands due to solid contact, whereas hydrodynamic lubrication effectively attenuates vibration energy and stabilizes spectral content. Furthermore, the sensitivity of the system dynamic response to variations in rotational speed is found to be significantly higher than to load variations. This study provides theoretical support for the optimization of lubrication strategies and vibration control in high‐power wind turbine gearboxes.