Research on flow rule and thermal dissipation between the rotor poles of a fully air-cooled hydrogenerator

Aiming at providing a theoretical basis for the 1000-MW giant fully air-cooled hydrogenerator, which is being studied and developed currently, this paper established a coupling calculation model of 3-D fluid and temperature field based on the actual structure and size of a 250-MW fully air-cooled fanless hydrogenerator. Fluid dynamics control equations, and corresponding boundary conditions in the solved region were given. The additional losses from electromagnetic field calculation were applied to the coupling model as heat sources. Using a computational fluid dynamics approach, the flow distribution of cooling air and the temperature distribution of rotor structures were obtained. It focused on the axial and radial variation rules of the flow condition of cooling air between adjacent poles. Meanwhile, it conducted a detailed research study on the variation rule of the heat-transfer coefficients of pole shoes and damping bars. Temperature calculated value of exciting windings was coincident well with the measured value. The calculated error between the two values meets the engineering requirement, thus verifying both applicability and accuracy of the solution method this paper presents.