Flow and heat transfer characteristics and cooling-structure optimization of a fully radial-ventilated rotor in a 1000-MW nuclear turbine generator

The turbine generator is the key energy-conversion equipment in the conventional islands of large nuclear power plants, and rotor cooling directly affects unit reliability. As unit capacity and rotor aspect ratio increase, longer internal flow paths intensify flow maldistribution among radial ventilation holes and local overheating. A three-dimensional flow and heat- transfer coupling model is established for the full radial ventilation rotor of a 1000 MW hydrogen-cooled turbo-generator. The effects of rotor-body length, sub-slot cross-sectional area, and supplementary inlet position on hydrogen flow and temperature were investigated. The results show that the radial hole flow rate of the original model is higher in the front end, lower in the middle and higher in the rear end, and the air supply in the middle is insufficient. Changing rotor-body length redistributed rear-end flow but caused a front-to-rear cooling imbalance. Raising the bottom surface of the sub-slot is beneficial to enhance the air supply in the middle and rear sections, but it will aggravate the uneven heat transfer in the front end. The offset of the supplementary inlet position to the rotor body can shorten the tuyere path and improve the front-end cooling. Raising the sub-slot bottom by 2 mm and shifting the inlet by 100 mm reduced the maximum temperature from 145.93 °C to 144.75 °C. The temperature difference of the typical aperture at the front end and the end is reduced from 35 °C and 15 °C to 33 °C and 12 °C, respectively. This combined design suppresses front-end hot spots while improving rear-end hydrogen supply, providing guidance for rotor cooling-structure design in large nuclear turbine generators.