Fuel recirculation system

Patent metadata

Field	Value
Publication number	US-11511878-B2
Application number	US-201916669847-A
Country	US
Kind code	B2
Filing date	Oct 31, 2019
Priority date	Jul 19, 2019
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

Disclosed are systems and methods for maintaining bulk fuel temperatures in an aircraft. In one aspect, a recirculation system causes fuel to be delivered from a relatively low point near the feed hopper of each tank on the aircraft to one or more outboard locations of the wings. Once there, the fuel, due to gravity, flows back over the lower skin of the wing in channels back towards the fuselage, thus cooling the fuel. In other aspects, control systems are disclosed that coordinate the recirculation based on fuel levels in the tanks and fuel temperatures. The control systems also utilize a fuel scavenge system to maintain acceptable temperatures in the tanks.

First claim

What is claimed is:

1. An aircraft system comprising:
a fuel tank;
a fuel delivery system configured to deliver fuel from an inboard location of the fuel tank to an outboard location of the fuel tank to reduce a temperature of the fuel, the fuel tank being: (i) located in a wing; (ii) defined by internal structures of the wing; or (iii) both; and
the fuel delivery system being configured to deliver the fuel via a main fuel line to a plurality of fuel outlets located at an outboard section of the wing, the plurality of fuel outlets being located to discharge such that inboard flow occurs due to gravity along at least a portion of a lower skin of the wing, thus reducing a temperature of fuel within the wing fuel tank; and
wherein the plurality of fuel outlets are oriented to deliver fuel into a plurality of channels, the plurality of channels being at least partially defined by longitudinally-extending structural configurations rising from an internal surface of the lower skin of the wing;
wherein each channel of the plurality of channels is paired with one fuel outlet to deliver fuel to the channel.

2. The system of claim 1 wherein the plurality of channels comprises three distinct channels including a central channel flanked by two outside channels, all of the three distinct channels being defined by the internal surface of the lower skin.

3. The system of claim 2 wherein the three distinct channels are defined laterally by structural configurations attached atop the lower internal surface of the skin, and extending along a length of the wing.

4. The system of claim 2 wherein at least one fuel outlet of the plurality of fuel outlets comprises:
a central outlet supplying fuel for the central channel by discharging fuel at a central outboard location near a head of the central channel; and
a pair of lateral outlets supplying fuel at a pair of outboard locations near a respective head of each of the two outside channels.

5. The system of claim 1 wherein the plurality of channels comprises five distinct channels including a central channel flanked by four outside channels, all of the five distinct channels being defined by the internal surface of the lower skin.

6. The system of claim 5 wherein the five distinct channels are defined laterally by structural configurations attached atop the internal surface of the lower skin.

7. The system of claim 5 wherein at least one fuel outlet of the plurality of fuel outlets comprises:
a central outlet supplying fuel to the central channel by discharging fuel at a central outboard location near a head of the central channel; and
four lateral outlets, each supplying fuel at outboard locations for each of the four outside channels.

8. The system of claim 1 wherein at least one structural cross member in the wing is configured to encounter the inboard flow, and that the at least one structural cross member is configured to allow flow through at least one aperture defined therethrough, the at least one aperture being located immediately above the lower skin.

9. The system of claim 8 wherein the at least one aperture defined in the at least one structural cross member is an enlarged hole adapted to allow increased flow around a stringer.

10. The system of claim 8 wherein the at least one aperture is an added laterally extending slot located between laterally spaced stringers.

11. The system of claim 8 wherein the at least one aperture comprises at least one enlarged hole adapted to allow increased flow around a stringer and to conform to a shape of the stringer, and at least one added aperture existing between laterally spaced stringers.

12. The system of claim 1 , wherein the fuel delivery system includes:
a pumping arrangement, the pumping arrangement creating pressure to transport fuel through the main fuel line to the plurality of fuel outlets in the outboard section, the pumping arrangement including one of the following sources: a) a dedicated fuel recirculation pump that is independent from a main engine fuel supply system; b) engine feed hopper pressure developed by fuel scavenge system pumps; or c) recirculation flow branched off from plumbing of the main engine fuel supply system.

13. The system of claim 1 , wherein the fuel delivery system is configured to control a bulk fuel temperature through either one or both of the following ways: a) modulating a recirculation flow; b) modulating a flow of warm engine motive flow fuel.

14. A fuel recirculation system, comprising:
a fuel line extending from an inboard section of a wing fuel tank to a plurality of fuel outlets located at an outboard section of the wing fuel tank;
a pump for creating pressure to transport fuel along the fuel line such that fuel discharged from the fuel line in the outboard section of the wing fuel tank and wherein the pressure creates a stream of fuel flow;
the wing fuel tank defined by a wing interior, the wing interior including a plurality of spaced-apart cross members and a plurality of spaced-apart longitudinal members; and
the plurality, of spaced-apart cross members each being configured to allow free flow around each of the plurality of spaced apart longitudinal members such that a gravitational force compels the stream of fuel flow along a lower wing skin towards the inboard section of the wing fuel tank thereby reducing a temperature of fuel within the wing fuel tank;
wherein each fuel outlet of the plurality of fuel outlets are located at a pre-determined distance away from an outer wing surface to reduce mixing and aeration of the fuel.

15. The fuel recirculation system of claim 14 , wherein the fuel line comprises a plurality of outlets fluidly coupled to the fuel line such that fuel is discharged in a respective plurality of stringer channels along the lower wing skin to increase an area of fuel distribution for further reducing the temperature of fuel.

16. The fuel recirculation system of claim 14 , wherein the stream of fuel flow is provided by one of the following sources: a) a dedicated fuel recirculation pump that is independent from a main engine fuel supply system; b) engine feed hopper pressure developed by fuel scavenge system pumps; or c) recirculation flow branched off from plumbing of the main engine fuel supply system.

17. The fuel recirculation system of claim 14 , wherein a bulk fuel temperature is controlled through either one or both of the following ways: a) modulating a recirculation flow; or b) modulating a flow of warm engine motive flow fuel.

18. The fuel recirculation system of claim 14 , wherein the plurality of spaced-apart cross members are ribs and the plurality of spaced-apart longitudinal members are stringers.

19. The fuel recirculation system of claim 14 , wherein the plurality of spaced-apart longitudinal members create a plurality of fuel flow channels therebetween.

20. A method of maintaining fuel temperatures below flash point temperatures, the method comprising:
upon sensing that a hulk fuel temperature is greater than a predetermined level, pumping fuel through a main fuel line to an outboard location in a wing fuel tank,
wherein the main fuel line branches into a plurality of smaller fuel lines to deposit fuel at a plurality of locations in the wing fuel tank,
wherein each fuel line of the plurality of fuel lines comprises a fuel outlet having an opening with a limited radius to act as a diffuser and limit velocity of the fuel exiting the main fuel line;
wherein an internal surface of the wing fuel tank is configured to allow a strea

Assignees

• Textron Innovations Inc

Inventors

• Dwier Thomas Edward
• Wellemeyer Robert G

Classifications

• B64C2003/143

  comprising interior channels · CPC title

• Y02T50/40

  Weight reduction · CPC title

• B64C3/14

  Aerofoil profile · CPC title

• B64D37/34 Primary

  Conditioning fuel, e.g. heating (during filling B64D37/18) · CPC title

• B64D37/04 Primary

  Arrangement thereof in or on aircraft · CPC title