Self-pumping flywheel cooling system

1. A flywheel system comprising:

a flywheel rotor, rotatably mounted within the flywheel system, the flywheel rotor comprising:

a rotor shaft comprising a central bore formed therethrough; and

an elongated fluid flow member disposed within the central bore of the flywheel rotor;

wherein the elongated fluid flow member comprises:

an inner passage;

a dam disposed on a first end of the inner passage, the dam comprising a central opening;

wherein the inner passage is open at a second end, and

an outer passage that surrounds the inner passage;

wherein the outer passage is closed on an end surrounding the second end of the inner passage,

wherein the outer passage is open on an end surrounding the first end of the inner passage, and

wherein the inner passage and the outer passage are fixedly attached to the rotor shaft,

wherein hydrostatic pressure causes cooling fluid from a fluid reservoir to flow into the inner passage extending into the fluid reservoir at the first end, via the central opening of the dam;

wherein rotation of the inner passage of the elongated fluid flow member together with the flywheel rotor causes the cooling fluid to accumulate along a wall of the inner passage,

wherein the dam prevents the cooling fluid from exiting the inner passage at the first end, thereby causing the cooling fluid to propagate along the inner passage,

wherein the cooling fluid exits the inner passage at the second end and is released into the outer passage;

wherein the closed end of the outer passage prevents the cooling fluid from exiting the outer passage at the end surrounding the second end of the inner passage, thereby causing the cooling fluid to propagate along the outer passage until released from the open end of the outer passage into the fluid reservoir.

2. The flywheel system of claim 1 further comprising:

a fluid nozzle comprising a nozzle tip,

wherein the nozzle tip extends into the inner passage via the central opening of the dam;

wherein cooling fluid from the fluid reservoir, forced by the hydrostatic pressure, flows through the fluid nozzle, via an opening at the nozzle tip, past the dam, into the inner passage at the first end.

3. The flywheel system of claim 1 ,

wherein the elongated fluid flow member comprises:

an inner tube that provides the inner passage;

an outer tube that surrounds the inner tube; and

wherein an outer surface of the inner tube and an inner surface of the outer tube define bounds of the outer passage that surrounds the inner passage, and

wherein, in a second end region of the elongated fluid flow member, the inner passage and outer passage are open, thereby forming a fluid path from the inner passage to the outer passage.

4. The flywheel system of claim 1 ,

wherein the elongated fluid flow member comprises:

a tube that provides the inner passage; and

wherein an outer surface of the tube and an inner surface of the central bore define bounds of the outer passage that surrounds the inner passage, and

wherein, in a second end region of the elongated fluid flow member, the inner passage and outer passage are open, thereby forming a fluid path from the inner passage to the outer passage.

5. The flywheel system of claim 4 , wherein the outer passage is open to the fluid reservoir thereby forming a fluid path from the outer passage to the fluid reservoir.

6. The flywheel system of claim 1 , wherein the fluid reservoir comprises a plurality of cooling fins to increase a surface area available for heat removal.

7. The flywheel system of claim 1 , further comprising a stationary perforated cylinder that surrounds the inner passage of the elongated fluid flow member, wherein the stationary perforated cylinder is at least partially submerged in the cooling fluid reservoir.

8. A method for cooling a flywheel system comprising:

a flywheel rotor rotatably mounted within the flywheel system, the rotor comprising:

a rotor shaft comprising a central bore formed therethrough; and

an elongated fluid flow member disposed within the central bore of the flywheel rotor,

wherein the elongated fluid flow member comprises:

an inner passage; and

a dam disposed on a first end of the inner passage, the dam comprising a central opening,

wherein the inner passage is open at a second end, and

an outer passage that surrounds the inner passage,

wherein the outer passage is closed on an end surrounding the second end of the inner passage,

wherein the outer passage is open on an end surrounding the first end of the inner passage, and

wherein the inner passage and the outer passage are fixedly attached to the rotor shaft;

the method comprising:

arranging a fluid reservoir so as to be in fluid communication with the elongated fluid flow member; and

rotating the inner passage of the elongated fluid flow member together with the flywheel rotor to cause cooling fluid entering from the fluid reservoir and flowing into the inner passage at the first end, by hydrostatic pressure, to accumulate along a wall of the inner passage;

wherein the dam prevents the cooling fluid from exiting the inner passage at the first end, thereby causing the cooling fluid to propagate along the inner passage,

wherein the cooling fluid exits the inner passage at a second end and is released into the outer passage;

wherein, the closed end of the outer passage prevents the cooling fluid from exiting the outer passage at the end surrounding the second end of the inner passage, thereby causing the cooling fluid to propagate along the outer passage until released from the open end of the outer passage into the fluid reservoir.

9. The method for cooling a flywheel system of claim 8 , further comprising preventing,

by a stationary perforated cylinder that surrounds the first end of the elongated fluid flow member,

the development of a fluid vortex inside the fluid reservoir.

10. The flywheel system of claim 1 , wherein the flowing of the cooling fluid from the fluid reservoir into the inner passage does not require a pump.

11. The flywheel system of claim 8 , wherein the flowing of the cooling fluid from the fluid reservoir into the inner passage does not require a pump.