Transient analysis of non-uniform tilting-pad journal bearing for wind turbine main shaft under dynamical loading

Abstract

The non-uniform distributed tilting-pad journal bearing (NDTPJB), designed for large megawatt wind turbine main shafts, has not been assessed for transient stability under typical random wind conditions. Particularly, the dynamic interaction between low-speed, heavy-load operations with varying magnitude and direction, and the bearing's asymmetric structure, has not been fully explored. A new transient tribo-dynamic model is developed to analyze 6MW wind turbine's NDTPJB transient friction behavior, accounting for variable wind loads, pad distribution asymmetry, mixed lubrication (ML), and elastic pivot effects. Key parameters affecting tribo-dynamic friction performance—pad wrap angle, pad distribution count, and pivot stiffness—were comprehensively investigated. Findings show that dynamic loading cause asymmetrical behaviors in main and secondary pads, with performance significantly affected by the number of bottom distributed pads and improved stability with setting the number of above distributed pads to three. The stiffness of pivots significantly and complexly affects bearing dynamics, optimization of stiffness should be conducted after pad distribution determination. These discoveries guide further research and enhancements of NDTPJB in large rotating machinery under low-speed and heavy-load conditions.