Study On The Rotor Cooling Of Large4-Pole Turbine Generator

A large amount of heat is produced in the generator sets during operation, mainlyfrom the heat consumption of embedded copper coil in the generator rotor and stator.Generators overheating will greatly affect the work performance and life of entiregenerator set. Nowadays, the domestic turbine generator above600MW grade is usuallycooled by the method called water-hydrogen-hydrogen cooling method, which usinginternal water cooling for stator coil, external hydrogen cooling for stator core andinternal hydrogen cooling for rotor coil. Because of the specific heat capacity of water isrelatively large and the good cooling effect of the stator, so the stator coil temperature isgenerally lower. Therefore, Ventilation and cooling of the rotor become the focus of thestudy of ventilation and cooling of the whole turbine.Due to turbine’s large-scale, complex structure, the numerous air ducts which havea huge difference on the geometry size with turbine, the current computer software andhardware resources can not support the direct numerical simulation of the completeventilation and cooling system. Therefore, in this paper, a research idea of partialdecomposition is employed and a large4-pole turbine generator is taken as the researchobject. This paper focuses on the ventilation and cooling of turbine rotor, and simplifies,modeling, numerically simulate and analyze the ventilation and cooling system ofturbine generator. The main work of this thesis is as follows:Firstly, set up the generator stator wind groove element model, obtain the flowcharacteristics and laws of the stator wind groove element with eight different inflowvelocity conditions by computational fluid dynamics numerical simulation based on thefinite volume method.Secondly, build the ventilation and cooling model for end of the generator rotor, inwhich the stator region is simplified by using porous media model; numericallysimulate and analyze the flow field in static and dynamic conditions, obtain the eachbranch of flow distribution in the end of generator and the damping characteristicscoefficient for all ducts with eight different inflow velocity conditions.And then, further locally study the flow field and temperature field for the ends ofthe6th coil due to the maximum temperature rise is performed, numerically simulatethe flow field and temperature field for end of the6th rotor coil duct and the copper coilsurface temperature distribution, determine the maximum temperature rise; simulate the end of6th coil duct ventilation cooling with different hydrogen flow conditions, obtainthe fluid temperature in the coil duct and the surface temperature.Finally, set up model for gas cooling in the generator rotor body, in which thestator region is simplified by using porous media model, numerically simulate the flowin the generator rotor body unit with the rated inflow velocity73.3m/s and68m/s, andobtain flow distribution in each radial wind ditch of the rotor body, then analyze thehydrogen temperature in generator rotor body unit and get the copper coil temperaturevariation along the axial direction at the same time.