Calculation And Analysis Of Multi-Phases Fields In Large Air-cooled Turbogenerator

With the increase of turbogenerator capacity, the heat transferability of cooling system is becoming more and more vital to the insulation reliability. By reasonable optimizing the stator structure in a turbogenerator, utilization rate of coolant could be improved, and the maximum temperature of turbogenerator could be reduced. Considering the characteristics of fluid-flow and heat-transfer of a 200 MW air cooled turbo generator, the 3-D mathematical and physical model of stator end and multipath ventilation system for fluid and temperature coupling analysis were established, which were calculated numerically by using finite volume method (FVM), based on some corresponding boundary conditions and assumptions. In this process, the outlet flow rate of stator end and the distribution characteristic of fluid velocity around stator end windings and pressure plate were solved, so the boundary conditions of each inlet in the solving domain and heat transfer coefficients of stator end parts were determined. Stator winding, iron core, pressure finger and pressure plate temperature distribution were analysized under different heat transfer coefficient of stator end winding and pressure plate. Theoretical approach together with experimental results confirms the validity of the proposed method, including flow distribution obtained by mathematical and physical model of stator end, the boundary conditions of each inlet and assumptions in the model. The conclusion provides important method and theory basis for heat transfer coefficient determination of stator end in large generators. It provides important theoretical base for design of ventilated structure of Large Air-cooled Turbo-generator.Based on the experimental data and plenty of related operations above, two optimization designs about stator structure were proposed. With CFD principle and 3-D finite volume method, the modeling equations of air turbulent flow in cooling ducts were solved, and the effect of the ventilations'structure changing on coolant utilization ratio and distribution of stator temperature were studied. The study shows that, by adopting the two optimal structures, coolant can take away more heat from generator and the maximum temperature of generator can be reduced up to 9.13℃more than original structure.