Bearing Design Exceeded Expectations

WD power was contracted to design a unique Hydro-Dynamic bearing for a Horizontal Kaplan Turbine main rotor bearing in 2013. The requirements were quite challenging due to the forces involved and the restricted space available to fit the bearing.

The requirement was for a white metal sleeve bearing, lubricated by forced fed oil system. At the time, the rotor weight of 12 tons on the journal was higher than anything we have done before.

Using two different methods to the determine the bearing geometry, a high confidence level could be obtained. Due to the critical nature of this bearing, the design was verified with an independent party.

Once the design was completed, manufacturing commenced of this unique bearing design and special attention was given to transferring the load from the bearing shell to the support flange. A FEA model was prepared to determine bearing deflections, as any uneven deflection would have caused a misalignment with the shaft. The design also had to cater for easy starting as no hydraulic lift system could be implemented. Although the system was pressure fed, it had to be able to run down without power and the final challenge was to cater for a 100% run-away speed.

Due to the size and practical implications, testing was not an option and the first test was during commissioning on site. This went very well and the bearings actually exceeded all expectations in managing vibrations, heat generated and ability to operate without forced lubrication. The first three bearings are now operational for three years and annual inspections showed that they are in a good condition. A second, similar, design was also implemented in two similar, but larger turbines obtaining outstanding results, currently in operation.