Configuration performance of main shaft bearings for transient-loaded wind turbine

Abstract

Wind turbine (WT) main shaft bearings are currently dominated by rolling bearings. However, as the power capacity of WT increases, sliding bearings with lower cost and higher reliability present a more advantageous alternative. During the gradual application of sliding bearings, issues of high friction and wear have emerged. Due to the lack of tribological analysis methods for main shaft sliding bearings, it is difficult to reveal their friction and wear mechanisms and conduct optimized design. To address this, a novel and systematic 6-degree-of-freedom tribo-dynamic model for the main shaft sliding bearing system is developed, incorporating the elastic deformation of composite bearing pads. Based on this model, the effects of various pad configurations of segmented journal/thrust bearings on the tribo-dynamic performance under startup wind loads are analyzed. The results indicate that transient wind loads place the main shaft in a low-speed, high-load state, leading to a decline in oil film lubrication performance during the startup phase. Under these conditions, the 9-Pad journal bearing creates a more compatible radial clearance between shaft and pads, enhancing oil film performance and reducing surface contact. This improvement is attributed to the deformation at the edges of composite pads. The thrust bearing pad configurations affect both the dynamics of main shaft and the tribology of journal/thrust bearings, with the 6-Pad showing certain advantages. These findings can provide guidance for the configuration design of sliding bearings in WT main shaft.