Numerical study on heat transfer mechanism and structure optimization of hydro generator bearing cooler

Bearing is an important support to carry radial force and axial force, when hydro generator set is running, a large amount of heat produced by the rotor shaft and bearing touching will yield oil mist and jeopardize equipment health. The cooler can take away the heat in time, therefore, improving the cooler's efficiency is of great significance. In this paper, the internal structure of a turbine water guide-bearing semi-ring cooler at a hydro plant is optimized and numerical calculation is carried out to study heat transfer performance under three operating conditions. The results show that, the proposed spiral twisted flat tube cooler effectively reduces the risk of heat exchange tube blockage and significantly improves cooler heat exchange efficiency. Compared to prototype cooler, heat transfer power for the optimized cooler with spiral twisted flat tube increases by 43.8%, 62.2%, and 73.8%, respectively. Optimizing spacer plate positions at the cooler's inlet and outlet further enhances heat transfer power by 47.2%, 52.4%, and 56.4%, respectively. The pressure, velocity, and other parameters of cooler are also improved after both types of optimization compared to the prototype. The findings provide a reference for improving the thermal performance of guide bearings. •The heat transfer equation for the cooler is presented.•Operating principle of the radiator is explained using numerical simulation.•The application of spiral flat pipe adds the heat transfer coefficient and area.•Optimization of the bulkhead position results in increased heat transfer coefficient.•Both optimized solutions provide significant improvements in cooler performance.