The subject matter disclosed herein relates to the art of generators and, more particularly, to a generator including a multiple pass axially cooled stator.
Some conventional generators utilize a radial air flow to cool internal components. In particular, axial air flows are directed through a stator portion of the generator. The stator includes a plurality of passages that serve as a conduit for a cooling airflow. The cooling air flow is passed, in one direction, through the plurality of passages to conduct heat away from the stator. By lowering internal stator temperatures, generator efficiency is enhanced.
Smaller generators, such as those employed in wind turbines, may also employ stators having axial flow passages. However, some generator designs employ a shorter stator length. As such, the cooling airflow is not utilized efficiently. More specifically, the shorter stator length and correspondingly shorter axial flow passage do not provide adequate time for sufficient heat transfer between the stator and the air flow. Accordingly, in shorter generators, exit temperature of the cooling air flow is much lower than the exit temperature of the cooling air flow in larger generators. As a consequence, heat carrying capacity of the cooling air flow is under utilized.