Cyclonic separator

1. An aircraft fuel system comprising: a fuel tank; and a cyclonic separator comprising: a separation chamber; an inlet in fluid communication with the fuel tank and the separation chamber; a fuel outlet in fluid communication with the separation chamber; and a water outlet, wherein the cyclonic separator, inlet and outlet are shaped and configured to cyclonically separate a tangentially directed fuel-water mixture so as to discharge water from the water outlet and relatively less dense liquid fuel from the fuel outlet, and wherein the cyclonic separator is defined at least in part by a permeation member formed from a water-permeable material which enables water in the separation chamber to flow through the water-permeable material and out of the water outlet, but substantially prevents liquid fuel in the separation chamber from doing so.

2. The aircraft fuel system of claim 1 comprising a wall which defines the separation chamber, wherein the wall symmetrically extends around a centrally disposed, longitudinal axis; wherein the permeation member forms at least part of the wall; and the permeation member also symmetrically extends around the centrally disposed, longitudinal axis.

3. The aircraft fuel system of claim 1 wherein the water-permeable material comprises graphene oxide.

4. The aircraft fuel system of claim 1 further comprising a porous support structure which supports the permeation member, wherein the porous support structure has pores which enables water in the separation chamber to flow through the pores and out of the water outlet.

5. The aircraft fuel system of claim 1 further comprising an engine feed system arranged to feed liquid fuel from the fuel tank into an engine, wherein the water outlet of the cyclonic separator is in fluid communication with the engine feed system.

6. The aircraft fuel system of claim 1 , wherein the fuel outlet of the cyclonic separator is in fluid communication with the fuel tank.

7. The aircraft fuel system of claim 1 , wherein the liquid fuel is less dense than water.

8. The aircraft fuel system of claim 1 , wherein a cross sectional area of the separation chamber decreases toward a bottom of the separator.

9. The aircraft fuel system of claim 1 , wherein the inlet of the cyclonic separator is connected to a fuel feed line adapted to entrain a mixture of fuel and water or ice from a region of the fuel tank in which water or ice tends to collect.

10. The aircraft fuel system of claim 1 , wherein the inlet of the cyclonic separator is connected to a fuel feed line adapted to entrain a mixture of fuel and water or ice from a sump of the fuel tank.

11. An aircraft including the aircraft fuel system of claim 1 .

12. An aircraft fuel system comprising: a fuel tank; and a cyclonic separator comprising: a separation chamber; an inlet in fluid communication with the fuel tank and the separation chamber; a fuel outlet in fluid communication with the separation chamber; and a water outlet, wherein the cyclonic separator is adapted to discharge water from the water outlet and relatively less dense liquid fuel from the fuel outlet, and wherein the cyclonic separator further comprises a permeation member formed from a water-permeable material, wherein the separation chamber is defined by an inner wall comprising the permeation member; the cyclonic separator further comprises an outer wall which surrounds the inner wall, and a cavity between the inner wall and the outer wall; and the water outlet is in fluid communication with the cavity, wherein the cyclonic separator is adapted to discharge water from the water outlet via the cavity and relatively less dense liquid fuel from the fuel outlet, and the permeation member enables water in the separation chamber to flow through the water-permeable material into the cavity, but substantially prevents liquid fuel in the cyclonic separator from doing so.

13. The aircraft fuel system of claim 12 , wherein an inner surface of the outer wall includes a hydrophobic coating.

14. The aircraft fuel system of claim 12 wherein the inner wall, the outer wall, and the cavity each have a portion with a frusto-conical shape.

15. A fuel system comprising: a fuel tank; an engine feed system arranged to feed liquid fuel from the fuel tank into an engine; and a cyclonic separator comprising: a separation chamber; an inlet in fluid communication with the fuel tank and the separation chamber; a fuel outlet in fluid communication with the separation chamber; and a water outlet, wherein the cyclonic separator inlet and outlet are shaped and configured to cyclonically separate a tangentially directed fuel-water mixture so as to discharge water from the water outlet and relatively less dense liquid fuel from the fuel outlet, and wherein the cyclonic separator is defined at least in part by a permeation member formed from a water-permeable material which enables water in the separation chamber to flow through the water-permeable material and out of the water outlet, but substantially prevents liquid fuel in the separation chamber from doing so, wherein the water outlet of the cyclonic separator is in fluid communication with the engine feed system.

16. The fuel system of claim 15 wherein the water outlet of the cyclonic separator is in fluid communication with the engine feed system via a discharge line, and the discharge line has an outlet positioned adjacent an inlet of the engine feed system.

17. The fuel system of claim 15 wherein the water outlet of the cyclonic separator is in fluid communication with the engine feed system so that the water discharged from the water outlet of the cyclonic separator flows directly into the engine feed system.

18. The fuel system of claim 15 , wherein the water-permeable material comprises graphene oxide.

19. A cyclonic separator comprising: a separation chamber; an inlet in fluid communication with the separation chamber; a fuel outlet in fluid communication with the separation chamber; and a water outlet, wherein the cyclonic separator inlet and outlet are shaped and configured to cyclonically separate a tangentially directed fuel-water mixture so as to discharge water from the water outlet and relatively less dense liquid fuel from the fuel outlet, and wherein the cyclonic separator is defined at least in part by a permeation member formed from a water-permeable material which enables water in the separation chamber to flow through the water-permeable material and out of the water outlet, but substantially prevents liquid fuel in the separation chamber from doing so, wherein the water-permeable material comprises graphene oxide.

20. The cyclonic separator of claim 19 , wherein the water-permeable material comprises a layered structure of graphene oxide crystallites.