The influence of installation deviation on the upper guide bearing thermo-hydrodynamic characteristics of a 1000 MW giant hydropower unit.

This article focuses on the thermo-hydrodynamic (THD) analysis of the upper guide bearing in a 1000 MW giant Francis turbine unit, examining lubrication characteristics, flow behavior, and the effects of installation deviations. Using a three-dimensional numerical model that includes the entire bearing pads, oil tank, and internal cooler, the study finds that the cooler effectively reduces oil temperature but has minimal impact on pressure and velocity distributions within the oil film. Flow analysis via the Q-criterion reveals that high-velocity and strong vortex regions are concentrated mainly in the rotating oil line and oil film, while chaotic vortices in the oil tank exhibit low velocity and vorticity. Installation deviations show that radial displacement of pads outward increases oil film thickness and reduces pressure and temperature, whereas uniform shifting of pads to one side raises pressure, temperature, and unbalanced radial forces, leading to uneven temperature distribution and potential operational risks. The study also quantifies energy dissipation in the bearing, identifying wall dissipation as the dominant contributor, and provides insights to guide engineering practice for stable and efficient turbine operation.