Dynamic characteristics of wind turbine gearbox influenced by journal bearing

• Planet gear deformation under combined meshing and film pressure forces. • 6-DOF rigid-flexible coupled tribo-dynamic model of WTG with PGJB. • Differential modification effects on gear meshing and PGJB lubrication. • Full-scale experimental validation of WTG and PGJB models. Journal bearings are increasingly being used to support planetary gears in wind turbine gearboxes (WTG) due to their high load capacity and compact radial dimensions. However, the intermediate oil return groove (IORG) structure of planetary gear journal bearings (PGJB) increases the risk of contact and further complicates the coupling effects between elastohydrodynamic (EHD) lubrication and gear meshing. Few studies have investigated the impact of PGJB on the dynamic characteristics of WTG from a system perspective. To address this, a 6-degree-of-freedom (DOF) rigid-flexible coupled tribo-dynamic model of WTG with PGJB is established, considering the multi-pair, multi-tooth, and multi-point meshing characteristics of the planetary gear system (PGS). In this model, the PGJB is defined as a spring-damper unit, with dynamic coefficients determined by a transient mixed EHD model of PGJB, incorporating the elastic deformation under combined meshing and film forces. The influence mechanisms of IORG and modifications on gear meshing and PGJB lubrication performance are investigated and full-scale experimental validated. The results indicate that dynamic gear meshing excitation induces an upwind load bias in both the film pressure and the tooth surface force. The IORG enhances the misalignment resistance of PGJBs and further mitigates load bias during gear meshing. However, excessive modifications typically lead to asperity contact in the IORG region. Importantly, due to variations in dynamic meshing excitations among planetary gears within the PGS, identical modification parameters result in different lubrication effects on individual PGJBs, directly influencing the load-sharing characteristics of the WTG.