Power loss investigation of ball bearings considering rolling-sliding contacts

Ball bearings in liquid rocket turbopumps usually generate a large amount of power loss as they operate under extreme conditions, including cryogenic fluids, solid lubrications and extra high loads and speeds. However, to explore the power loss mechanism, a bearing theoretical model considering the influence of cryogenic fluid and solid lubricant is needed. In this paper, by introducing the newly developed fluid resistance forces and the rolling contact traction model into the equilibrium equations of the bearing, a new fluid-structure interaction-based quasi-static model is proposed, which can well simulate the rolling-sliding behaviour of balls under solid lubrication conditions. Based on tribology and kinematic analysis, eight power loss components of the bearing are deduced. The proposed model is validated by comparison with both experiments and existing theoretical methods. The results show that sliding, spinning and hydraulic power losses are the most important components of the bearing. Moreover, tribological behaviour, including creeping, skidding and spinning of the ball, is a key factor affecting the distribution of the power loss components. Utilizing the proposed model, the proportion of load-dependant power loss can be optimized to improve the anti-wear and heat-resisting properties of cryogenic ball bearings.