Cooling system for rotating machine

1. An electrical machine comprising:

a rotor having a rotatable shaft with an outer surface and a plurality of radial protrusions extending radially from the outer surface of the shaft, each of the protrusions having at least one cavity extending therethrough;

a stationary shaft disposed concentrically within the rotatable shaft and including an interior hollow region, wherein an annular space is formed between the stationary and rotatable shafts; and

a plurality of magnetic segments disposed on the radial protrusions,

wherein a fluid path extends from the hollow region, into the annular space, and through the cavities of the radial protrusions.

2. The electrical machine of claim 1 , wherein the radial protrusions extend along an axial portion of the rotating shaft.

3. The electrical machine of claim 1 , wherein each magnetic segment comprises a plurality of laminated magnetic sheets.

4. The electrical machine of claim 3 , further comprising permanent magnets interposed between respective pairs of adjacent magnetic segments.

5. The electrical machine of claim 1 , wherein each of the protrusions comprises a hole in fluid connection with a respective one of the cavities.

6. The electrical machine of claim 1 , wherein the annular space comprises baffles.

7. The electrical machine of claim 1 , further comprising a coolant within the fluid path.

8. The electrical machine of claim 7 , further comprising a seal between the rotating shaft and the stationary shaft.

9. The electrical machine of claim 8 , wherein the seal facilitates a change in reference frame of the coolant from rotating frame to stator frame.

10. An electrical machine comprising:

a stator comprising stator coils interposed between stator laminations;

a rotor having a rotatable shaft with an outer surface and a plurality of radial protrusions extending radially from the outer surface of the shaft, each of the protrusions having at least one cavity extending therethrough;

a stationary shaft having a hollow region and disposed concentrically within the rotatable shaft, wherein an annular space is formed between the stationary and rotatable shafts, wherein a fluid path extends from the hollow region, into the annular space, and through the cavities of the radial protrusions;

a plurality of magnetic segments disposed on the radial protrusions; and

a seal disposed between the stationary shaft and the rotatable shaft enclosing the annular space and comprising a pathway to an exit.

11. The electrical machine of claim 10 , further comprising at least one baffle disposed in the fluid path.

12. The electrical machine of claim 11 , further comprising at least one baffle disposed within the annular space.

13. The electrical machine of claim 10 , wherein the radial protrusions comprise axial fins.

14. The electrical machine of claim 13 , wherein the axial fins comprise axial holes coupled to the fluid path.

15. A rotor cooling system comprising:

an annular space defined between a rotatable shaft and a hollow stationary shaft, the rotatable shaft having an outer surface and a plurality of radial protrusions extending radially outward from the outer surface;

a fluid path from within the hollow stationary shaft and into the annular space;

a plurality of cavities, each extending radially from the annular space towards a periphery of a respective one of the radial protrusions; and

holes in the radial protrusions, each being in fluid connection with a respective one of the plurality of cavities.

16. The rotor cooling system of claim 15 , wherein the annular space, the radial cavities, and the axial holes are coupled to form the fluid path.

17. The rotor cooling system of claim 16 , further comprising a coolant circulating within the fluid path.

18. The rotor cooling system of claim 17 , wherein the coolant traverses between rotating and stationary frames.

19. The rotor cooling system of claim 18 , wherein a seal facilitates traversal of the coolant between rotating and stationary frames.