Hydrodynamic film thickness measurements and CFD analysis identify the root causes of repetitive thrust bearing failures on a 45 MW hydro generating unit at Hydro-Québec

28th IAHR symposium on Hydraulic Machinery and Systems

Gauvin, P.^1 ; Huard, P.^1

Hydro-Québec Production, Division Expertise de Centrales, Canada^1

关键词: Acceptable limit;    Bearing failures;    Hydrodynamic films;    Hydrodynamic pressure;    Oil cooling system;    Oil film thickness;    Production stoppage;    Significant surfaces;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/49/7/072013/pdf
DOI  :  10.1088/1755-1315/49/7/072013

来源: IOP

【 摘 要 】

High temperature level recorded on the thrust bearing of a 45 MW hydro generating unit was resulting in frequent production stoppage. In spite of improvements brought to the oil cooling system since the rehabilitation in 2008, the operator had to activate the bearing oil lift system to keep the temperature below acceptable limits. Primary root cause analysis first pointed to the design of the shoe that was centrally pivoted, not allowing the formation of a thick hydrodynamic film. The removal of a strip of the soft metal layer near the trailing edge of the shoe resulted in a significant surface temperature reduction (about 15 deg. C), as predicted by a CFD model of the oil film. The goal of this machining was to increase the pivoting angle by moving the centre of hydrodynamic pressure. Proximity sensors were installed at each corner of the redesigned shoe to measure the film thickness and the bearing attitude. Signal analysis revealed a step of a magnitude close to the oil film thickness between the two halves of the rotating thrust block. This was the cause of another failure few hours since restarting the unit. The lessons learnt through these measurements and analyses were carefully applied to the ultimate build. The unit now runs with a robust thrust bearing and even survived a significant cooling flow reduction event. This paper presents the CFD analysis results and the measurements acquired during these events.