Abstract: In the rotor ventilation system with radial ducts, the configuration parameters of sub slot, the distribution of radial ducts, and the diameter of slot wedge directly affect the flow characteristics of coolant in cooling ducts. To reduce temperature difference and thermal stress along axis direction of large turbo generator rotor, the coolant mass flow rate distribution in radius ducts along axis direction of rotor must be uniform. Based on the characteristics of radial ventilation system, a discrete calculation model of the coolant flow distribution of radial ventilation system is built. The computation results of rotor ventilation systems of a 125 MW air-cooled and a 300 MW water-hydrogen-hydrogen-cooled turbine generator with radial ducts are provided. The effect of the configuration parameters of sub slot on mass flow rate distribution in radial ducts is presented. The results show that the tapered sub-slot can provide more uniform coolant mass flow rate distribution in radial ducts, and there exists optimum tilt angle of sub-slot. The results are helpful to the design of radial ventilation system of turbo generator rotor.

Key words: Discrete model, Flow deviation, Radial ventilation, Rotor, Turbo-generator