Heat transfer in air-gap and thermal-fluid coupling field of a large-scale turbine generator.

With the capacities of large-scale turbine generators increase, higher electrical and thermal loads may cause higher risk of thermal faults. Especially, for those air cooling machines with single channel ventilation system, the comparatively poor thermal conductibility of air makes the air-gap become a critical part in thermal transmission network. Thus, the heat transfer in air-gap of large scale turbine generators is followed with interest. The investigation is performed on a 150 MW air cooling turbine generator with single channel ventilation cooling system, and realized via the thermal-fluid coupling field studying. A nonlinear numerical calculation model for fluid flowing and heat transfer within the machine is proposed, and solved by finite volume method (FVM). Then, the heat transfer in the air-gap is analyzed, whilst the temperature distributions in machine different parts, as windings, stator core, and rotor components, are investigated. In addition, the velocity vector distribution of coolant in the ventilation system is also studied, and the air motion track in the air-gap is analyzed while considering the influence of rotor rotation. Finally, the influence of flow in the air-gap on fluid flowing in the stator radial ventilation ducts is investigated. [ABSTRACT FROM AUTHOR]