Influences of planet gear journal bearing on dynamic characteristics of megawatt-scale wind turbine drivetrains: Simulations and experiments

The planet gear journal bearing (PGJB) has compact dimensions and superior vibration- dampening properties and is gradually used to support planet gears in the gearbox of wind turbine drivetrain (WTD). However, there is a complex coupling between the structure deformation of drivetrain and film thickness of PGJB under heavy loads, causing edge contact of PGJB and reducing system stability. In this study, a tribo-dynamic coupling modeling method of WTD is developed considering the dynamic lubrication characteristics of PGJB. The elastic deformation of PGJB is considered by the finite element method, the average flow Reynolds equation is used to compute the dynamic film thickness of PGJB. Then the structure flexibility of WTD is considered by finite element condensation theory. Finally, a dynamic model of WTD with PGJB is established. The influences of operating conditions and PGJB structure parameters on the dynamic characteristics of WTD are investigated, and a test rig is conducted to validate the theoretical analysis. The results show an extra frequency related to the rotational frequency of planet gear in vibration displacement. PGJB is prone to solid contact under high-torque conditions. Reducing width-to-diameter ratio and radial clearance of PGJB can decrease system vibration and improve load-sharing performance of WTD.