A machine comprises: a rotor comprising (a) axially extending coils, each
coil extending into an endwinding region, (b) a plurality of cavities
between the coils in the endwinding region, and (c) a plurality of spacers
situated between the coils. Ventilation grooves having an inlet and an
outlet are defined in the rotor with at least some of the coils including
at least one of the ventilation grooves. The ventilation grooves provide
at least one path for gas flow from at least one first cavity to at least
one of (i) a second cavity or (ii) a different portion of the first
cavity.
