SUMMARY

This research studies the thermo-fluidic transport in the end-turn region of large-scale turbo-generator systems in the 350MVA machine class. The goal of the study is to quantify, characterize and explain the thermal transport using a simplified, fast-solving, parametric analytical code. The purpose of the analytical code is to predict the copper temperatures in the rotor end turns using a parametric approach to allow for rapid design sizing of the generator systems. The thermal management of the rotor system, including the end turns and associated insulation, is critical to increasing the performance, specifically generator efficiency, and output power rating of the generator system whilst maintaining the reliability and service life of up to 50 years. The study considers three primary research objectives: a) the description of the bulk flow and associated thermal transport in the rotor system, b) the construction of a parametric analytical description of thermal transport in a single rotor end-turn cell, and c) the construction of a parametric analytical tool for the prediction of copper temperatures in the circumferential cavities of the end-arc of the rotor end-turn region. The approach to the description of the bulk-flow in the circumferential that is adopted in this study is termed the virtual-pipe technique, wherein the majority of the transport in the cavity is defined to exist within a virtual pipe of a known hydraulic diameter. The transport in the circumferential cavities under different operating conditions are studied using large-scale CFD techniques. The analytical description of the single rotor end-turn cell and the combination of the cells to describe the copper temperatures throughout the end-arcs will be constructed using thermo-fluidic networks. The complete description of the multi-row end-turn region considers the variation in cavity geometry and the changes in the fluid temperature, velocity and pressure along the flow path described by the virtual pipe.