Numerical Studies on the Flow Field of Stator and Air Gap for Large Air-cooled Turbo-generator

In order to study the flow characteristics in the stator and air gap for a large air-cooled turbo-generator with multi-air-zone of stator, a 3-D physical model includes the stator, rotor, and air gap was established. Numerical simulation was carried out by the finite volume method according computational fluid dynamics (CFD) principle, based on some corresponding boundary conditions and assumptions. The results show that the cooling air flowing into the air-gap through the outlets of rotor wedge rotates with rotor in the spiral trajectory and in higher velocity than ambient. The air velocity alternate high and low in axial direction. There are different flow characteristics in different regions of the air gap because of the influence of stator and rotor radial air injection and axial through flow. The air flowing into the air-gap from the cold zone forms the secondary flow near the side of stator.