Rotor cooling

A rotating electrical machine comprising a rotor, a stator, and a fan for drawing cooling air axially through the rotating electrical machine, the rotor comprising:

• a plurality of salient poles;
• rotor windings wound on the salient poles;
• a plurality of spacers at spaced locations in an axial direction through the rotor windings, the plurality of spacers defining an axial cooling vent for the cooling air to pass axially through the rotor windings, each spacer comprising at least one axial air passage;
• and
• a winding support for supporting the rotor windings, at least one of the plurality of spacers held on the rotor by an interference fit between a pole shoe of one of the salient poles and a first side of the winding support,
• wherein a second side of the winding support comprises a deflector configured to deflect air flow into the axial cooling vent,
• wherein the rotor windings comprise a first set of windings and a second set of windings on a same pole of the plurality of salient poles, and the plurality of spacers are positioned between the first set of windings and the second set of windings to form the axial cooling vent between the first set of windings and the second set of windings,
• wherein the axial cooling vent formed by the plurality of spacers extends through the rotor windings in an axial direction and a substantially radial direction,
• wherein the axial cooling vent formed by the plurality of spacers extends in the axial direction from one end axially of one of the salient poles to another end axially of the salient pole, and
• wherein the axial cooling vent formed by the plurality of spacers extends in the substantially radial direction from one end radially of the first set of windings to another end radially of the first set of windings.

A method of winding a rotor for a rotating electrical machine, the rotor comprising a plurality of salient poles and a winding support, the method comprising:

• winding a pole of the plurality of salient poles with a first, inner set of windings;
• inserting at least one spacer on the first, inner set of windings, the at least one spacer comprising at least one axial air passage;
• and
• winding a second, outer set of windings of the pole on the at least one spacer;
• wherein the at least one spacer forms an axial cooling vent for cooling air produced by a fan to pass axially through the rotor windings between the first, inner set of windings and the second, outer set of windings, the axial cooling vent formed by the at least one spacer extending through the windings in an axial direction and a substantially radial direction,
• wherein the spacer is held on the rotor by an interference fit between a pole shoe of one of the salient poles and a first side of the winding support and a second side of the winding support comprises a deflector configured to deflect air flow into the axial cooling vent.