Investigation of Fluid Flow and Heat Transfer in a Turbogenerator Rotor With Alternating Radial Ventilation System

In order to suppress the overheating and thermal imbalance in the rotor winding of a turbogenerator with traditional dual radial ventilation ducts (DRVDs), an alternating radial ventilation system of the rotor in a 350 MW water-hydrogen-hydrogen-cooled turbogenerator is investigated and designed in this paper. Firstly, a global ventilation network containing alternating radial ventilation ducts (ARVDs) is established, followed by the results obtained via successive iterative method. Secondly, physical and mathematical models of the three-dimensional (3-D) fluid-temperature field in a rotor with ARVDs are built, accompanied by basic assumptions and corresponding boundary conditions, some of which are derived from ventilation network calculations. The fluid-thermal coupling analysis is performed using finite volume method (FVM). The calculated results agree well with the measured values, which verifies the accuracy of the calculation method and models. Then, the fluid velocity distributions at the entrance, exit and interior of the ARVDs as well as the heat transfer coefficients at the surfaces are analyzed, revealing the reasons for the superior heat dissipation capability over the DRVDs. The temperature variation rules of the winding and core are also studied. Furthermore, the influence of key parameters of ARVDs on the maximum temperature and thermal unbalance coefficient in rotor winding and core is discussed. The design considerations of ARVDs are finally summarized.