| This thesis summarizes the various cooling methods (water-cooling, air-cooling and evaporation-cooling) of the level of 700MW, as well as other large and middle hydro-generators, presents comparison and analysis to the characteristic and applicability of each method.The developing progress and achivements in ventilation and cooling of hydro-generators in domestic and abroad are summarized. Moreover, it makes the preliminary conclusion on the completing air-cooling method that was used in right bank of three gorges and laxiwa hydro-generators and proves the method's feasibility by calculation, analysis and test. This thesis gives a brief introduction of the basic principle for calculating cooling air flow by liquid continuity equation and net theory, and the basic principle of calculating the three-dimensional temperature field in stator and rotor of hydro-generators using finite element method. Take the right bank of three gorges hydro-generator for an example, the math model of ventilation system and temperature field are presented, the thesis introduces the calculation of hydro-generators about the ventilation system, stator and rotor temperature distribution using fluid mechanics software FLOWMASTER and finite element software ANSYS. The article makes preliminary analysis to the cooling effect, so the temperature distribution on hydro-generator's different part is mastered, and provides theoretical basis for completing air-cooling mode used for 700MW hydro-generators. The thesis adopts similitude theory to study ventilation system, which verifies the validity of real machine math model, inspects feasibility of ventilation system design and evaluates rationality of improving ventilation structure. Through comparison between analysis of the ventilation system and model test, the conclusion is obtained that it is absolutely feasible to adopt to completing air-cooling on 700MW hydro-generators that is representative of right bank of three gorges and laxiwa power station.
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