Multi-path cooling of a turbo-generator rotor winding

1. A turbo-generator comprising:

a rotor body defining an axis; and

a rotor winding disposed around the rotor body, the rotor winding including a sub slot, a plurality of first axial cooling ducts disposed in an axial direction and axially adjacent to each other and axially separated from each other by a first flow baffle to prevent cross flow, each first axial cooling duct having a first inlet and a first outlet, and a plurality of second axial cooling ducts disposed adjacent and parallel to the first axial cooling ducts and axially adjacent to each other for multi-path cooling, each of the second axial cooling ducts having a second inlet and a second outlet, wherein each first inlet is disposed axially offset from a respective second inlet and each first outlet is disposed axially offset from a respective second outlet.

2. The turbo-generator as recited in claim 1 , further comprising a main slot adjacent to the sub slot.

3. The turbo-generator as recited in claim 1 , further comprising at least a third axial cooling duct disposed adjacent to at least one of the first and second axial cooling ducts.

4. The turbo-generator as recited in claim 1 , wherein the first and second inlets communicate with the sub slot and the first and second outlets communicate with an outer circumference of the winding.

5. The turbo-generator as recited in claim 1 , wherein the first and second inlets and the first and second outlets are disposed such that a direction of coolant flow in each of the first and second axial ducts is the same as a direction of coolant flow in the subslot.

6. The turbo-generator as recited in claim 1 , wherein, at a center of the rotor winding, a flow cross-flow of a coolant through at least one of the first and second axial ducts is permitted.

7. The turbo-generator as recited in claim 1 , wherein, at a center of the rotor winding, at least one of the first and second outlets are disposed so as to prevent a cross-flow of coolant through the respective first or second axial duct.

8. The turbo-generator as recited in claim 1 , wherein at least a portion of one of the first and second axial ducts is enlarged.

9. A turbo-generator comprising:

a rotor body; and

a rotor winding disposed around the rotor body, the rotor winding including a sub slot, a plurality of first axial cooling ducts disposed axially adjacent to each other and axially separated from each other by a first flow baffle to prevent cross flow, each first axial cooling duct having a first inlet and a first outlet, and a plurality of second axial cooling ducts disposed adjacent and parallel to the first axial cooling ducts and axially adjacent to each other for multi-path cooling, each of the second axial cooling ducts having a second inlet and a second outlet, wherein each first inlet is disposed offset from a respective second inlet and each first outlet is disposed offset from the a respective second outlet, wherein a distance of the offset between first and second inlets is equal to a portion of a length at least one of the first and second axial ducts, and wherein the first outlet and the first inlet of axially adjacent first axial cooling ducts are axially separated by a flow baffle.

10. The turbo-generator as recited in claim 9 , wherein the lengths of each of the first and second axial ducts are equal.

11. The turbo-generator as recited in claim 9 , wherein the portion is one-half.

12. A turbo-generator comprising:

a rotor body; and

a rotor winding disposed around the rotor body, the rotor winding including a sub slot, a plurality of first axial cooling ducts disposed axially adjacent to each other and axially separated from each other by a first flow baffle to prevent cross flow, each first axial cooling duct having a first inlet and a first outlet, and a plurality of second axial cooling ducts disposed adjacent and parallel to the first axial cooling ducts and axially adjacent to each other for multi-path cooling, each of the second axial cooling ducts having a second inlet and a second outlet, wherein each first inlet is disposed offset from a respective second inlet and each first outlet is disposed offset from a respective second outlet, wherein a distance of the offset between first and second outlets is equal to a portion of a length at least one of the first and second axial ducts, and wherein the first outlet and the first inlet of axially adjacent first axial cooling ducts are axially separated by a flow baffle.

13. A rotor winding for multi-path cooling of a rotor defining an axis in a turbo-generator, the rotor winding comprising:

a main slot supplying a coolant;

a sub slot disposed adjacent to the main slot;

a plurality of first axial cooling ducts disposed in an axial direction and axially adjacent to each other and axially separated from each other by a first flow baffle to prevent cross flow, each first axial cooling duct having a first inlet connecting the sub-slot and a first outlet communicating with an outer circumference of the winding;

a plurality of second axial cooling ducts disposed adjacent and parallel to the first axial cooling ducts and axially adjacent to each other and each having a second inlet connecting the sub slot and a second outlet communicating with the outer circumference, wherein each first inlet is disposed axially offset from a respective second inlet and each first outlet is disposed axially offset from a respective second outlet.