Numerical Calculation of Fluid Heat Transfer in Rotor of Large Air-cooled Generator Based on Global Ventilation Network Model

Large-scale air-cooled generators are the most widely used generators, because of the weak effect of air cooling, its ventilation cooling has been the focus of research. The size of large generator is huge, the ventilation structure and flow state are complicated, and it is difficult to realize the calculation of global ventilation and cooling. Especially under the high pressure of wafter and the rotating centrifugal pressure, the internal air flow state and heat transfer characteristics of the rotor are difficult to accurately characterize. This paper presents a new calculation method for the coupling of totally enclosed circulation global ventilation network model with distributed parameters and local multi-physical field numerical model of rotor. Firstly, the generator global ventilation network model considering the specific structural parameters of axial and radial ventilation of the rotor sub-slot is established, and the distribution characteristics of flow and pressure in key wind regions are calculated. Secondly, a 3-D local coupling model of fluid and heat transfer for the rotor is established, and the fluid motion state, heat transfer characteristics of the rotor are further calculated based on the boundary conditions of the rotor ventilation parameters calculated by the global ventilation network model. Finally, the accuracy of the proposed method is verified by comparing the calculated results of the ventilation and temperature with the experimental data. The method can be used for rotor heat dissipation calculation and ventilation structure design of large generator.