Counter-rotating electric generator in turbine engine

1. A turbine engine comprising:

a compressor;

a turbine;

a drive shaft coupled to the compressor and the turbine, wherein the turbine is configured to drive the compressor via the drive shaft;

a tower shaft mechanically coupled to the drive shaft, wherein the tower shaft extends radially away from the drive shaft and wherein the tower shaft is driven by the drive shaft; and

an electric generator comprising:

a first rotating element comprising a magnet array, wherein the first rotation element is mechanically coupled to the tower shaft, and wherein the second rotating element is configured to rotate in a first direction coaxial with the drive shaft based on a rotation of the tower shaft, and

a second rotating element comprising a coil array wherein the second rotating element is mechanically coupled to the tower shaft, and wherein the second rotating element is configured to rotate in a second direction coaxial with the drive shaft based on the rotation of the tower shaft, wherein the second direction is opposite to the first direction.

2. The turbine engine of claim 1 , further comprising a slip ring configured to output electrical current generated by the coil array.

3. The turbine engine of claim 1 , further comprising a planetary gear-set, wherein:

the tower shaft is mechanically coupled to the drive shaft by at least the planetary gear-set;

the drive shaft is configured to rotate at a first angular velocity; and

the tower shaft is configured to rotate at a second angular velocity that is lower than the first angular velocity of the drive shaft.

4. The turbine engine of claim 1 , wherein:

the first rotating element is mechanically coupled to the tower shaft by at least a gear-set; and

the second rotating element is mechanically coupled to the tower shaft by at least the gear-set.

5. The turbine engine of claim 4 , wherein:

the gear-set comprises:

a gear mechanically coupled to the tower shaft,

a first pinion mechanically coupled to the first rotating element, and

a second pinion mechanically coupled to the second rotating element;

the first rotating element is mechanically coupled to the tower shaft by at least the first pinion mechanically coupled to the gear; and

the second rotating element is mechanically coupled to the tower shaft by at least the second pinion mechanically coupled to the gear.

6. The turbine engine of claim 5 , wherein:

the first pinion is mechanically coupled to a first side of the gear and configured to rotate in a third direction; and

the second pinion is mechanically coupled to a second side of the gear and configured to rotate in a fourth direction that is opposite to the third direction.

7. The turbine engine of claim 1 , wherein:

the magnet array is configured to rotate at a particular tangential velocity; and

the coil array is configured to rotate at the particular tangential velocity of the magnet array.

8. The turbine engine of claim 1 , wherein:

the first rotating element is configured to rotate at a first angular velocity;

the second rotating element is configured to rotate at a second angular velocity; and

the angular velocity of the first rotating element relative to the second rotating element is a sum of the first angular velocity and the second angular velocity.

9. A method for generating an electrical current with a turbine engine having an electric generator, the gas turbine engine comprising a compressor, a turbine, a drive shaft coupled to the compressor and the turbine, wherein the turbine is configured to drive the compressor via the drive shaft, a tower shaft mechanically coupled to the drive shaft, wherein the tower shaft extends radially away for the drive shaft and where in the tower shaft is driven by the drive shaft; and wherein the electric generator comprises a first rotating element comprising a magnet array, wherein the first rotating element is mechanically coupled to the tower shaft, and wherein the first rotating element is configured to rotate in the a first direction coaxial with the drive shaft based on a rotation of the tower shaft, wherein the electric generator further comprises a second rotating element comprising a coil array, wherein the second rotating element is mechanically coupled to the tower shaft, and wherein the second rotating element is configured to rotate in a second direction coaxial with the drive shaft based on the rotation of the tower shaft, wherein the second direction is opposite to the first direction, the method comprising:

receiving, at the first rotating element of the electric generator of the turbine engine, via the tower shaft, first mechanical power to cause the first rotating element to rotate in the first direction coaxial with the drive shaft;

receiving, at the second rotating element of the electric generator, via the tower drive shaft, second mechanical power to cause the second rotating element to rotate in the second direction that is opposite to the first direction coaxial with the drive shaft;

generating, at the coil array of the second rotating element and based on the first mechanical power and the second mechanical power, the electrical current; and

outputting, by an electrical output element of the electric generator, to an electrical load, the electrical current.

10. The method of claim 9 , wherein the electrical output element comprises a slip ring electrically connected to the coil array.

11. The method of claim 9 , wherein:

the tower shaft is mechanically coupled to the drive shaft by a planetary gear-set of the turbine engine; and

the planetary gear-set is configured to rotate the tower shaft at an angular velocity that is lower than an angular velocity of the drive shaft.

12. The method of claim 9 , wherein:

receiving the first mechanical power comprises receiving, at the first rotating element, via a gear-set mechanically coupled to the tower shaft, the first mechanical power; and

receiving the second mechanical power comprises receiving, at the second rotating element, via the gear-set, the second mechanical power.

13. The method of claim 12 , wherein:

receiving the first mechanical power comprises receiving, at the first rotating element, via a first pinion of the gear-set mechanically coupled to a gear of the gear-set, the first mechanical power; and

receiving the second mechanical power comprises receiving, at the second rotating element, via a second pinion of the gear-set mechanically coupled to the gear of the gear-set, the second mechanical power, wherein:

the gear is mechanically coupled to the tower shaft,

the first pinion is mechanically coupled to a first side of the gear and configured to rotate in a third direction, and

the second pinion is mechanically coupled to a second side of the gear and configured to rotate in a fourth direction that is opposite to the third direction.

14. The method of claim 9 , wherein:

receiving the first mechanical power comprises rotating a magnet array of the first rotating element at a particular tangential velocity; and

receiving the second mechanical power comprises rotating the coil array at approximately the particular tangential velocity of the magnet array.

15. The turbine engine of claim 1 ,

wherein the first rotating element is configured to rotate in the first direction about an axis passing through a center of the drive shaft, and

wherein the second rotating element is configured to rotate in the second direction about the axis passing through the center of the drive shaft.