AIRCRAFT INERTING SYSTEM

• US 20140238501A1
• Filed: 02/28/2014
• Published: 08/28/2014
• Est. Priority Date: 02/28/2013
• Status: Active Grant

• Current Assignee: Airbus Operations GmbH (Airbus SE), Airbus Operations Limited (Airbus SE)
• Original Assignee: Airbus Operations GmbH (Airbus SE), Airbus Operations Limited (Airbus SE)
• Inventors: TICHBORNE, Franklin, HUGHES, Brian, RENOUARD-VALLET, Gwnalle Marie Lucette, BURNELL, Stephen Edward
• Granted Patent: US 9,567,094 B2
• Time in Patent Office: Days
• US Class Current: 137/12
• CPC Class Codes: B64D 2041/005 Fuel cells
• CPC Class Codes: B64D 37/06 Constructional adaptations thereof
• CPC Class Codes: B64D 37/32 Safety measures not otherwise provided for, e.g. preventing explosive conditions extinguishing or preventing fires in aircraft A62C
• CPC Class Codes: Y02T 50/40 Weight reduction
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells
• CPC Class Codes: Y10T 137/0379 By fluid pressure
• CPC Class Codes: Y10T 137/3099 Float responsive

Abstract

A method of controlling a flow rate of inerting gas introduced into a vented aircraft fuel tank, the method comprising: monitoring changes in a quantity of a fuel in the aircraft fuel tank; monitoring changes in the ambient air pressure external to the aircraft fuel tank; and actively controlling a flow rate of inerting gas, {dot over (m)}(I), introduced into the aircraft fuel tank based upon changes in the quantity of fuel in the fuel tank and changes in the ambient air pressure, p. Also, an aircraft including a vented fuel tank, a supply of inerting gas for rendering inert the fuel tank ullage, and a controller for performing the method.

Claims

1. A method of controlling a flow rate of inerting gas introduced into a vented aircraft fuel tank, the method comprising:

monitoring changes in a quantity of a fuel in the aircraft fuel tank;

monitoring changes in the ambient air pressure external to the aircraft fuel tank; and

actively controlling a flow rate of inerting gas introduced into the aircraft fuel tank based upon changes in the quantity of fuel in the fuel tank and changes in the ambient air pressure, p.

2. A method according to claim 1, wherein the mass flow rate of the inerting gas is controlled such that the mass flow rate of the fuel tank ullage that is vented from the fuel tank is minimized.

3. A method according to claim 2, wherein the mass flow rate of the inerting gas is controlled such that the mass flow rate of the fuel tank ullage that is vented from the fuel tank is substantially zero during ground manoeuvring, cruise and descent operations.

4. A method according to claim 2, wherein the mass flow rate of the inerting gas is controlled such that the mass flow rate of the fuel tank ullage that is vented from the fuel tank is less than 2 g/s throughout all operational ground and flight phases of the aircraft except climb.

5. A method according to claim 1, wherein the step of monitoring changes in the quantity of fuel in the fuel tank includes reading a mass flow rate of fuel being consumed, e.g. by engine(s).

6. A method according to claim 1, further comprising calculating a net volume flow rate, Q(U_P), of ambient air into the fuel tank ullage, U, via its vent system due to changes in ambient air pressure, P.

7. A method according to claim 6, wherein the net volume flow rate of ambient air into the fuel tank ullage is calculated based upon a rate of change of the ambient air pressure, δ

P/δ

t, and the instantaneous fuel tank ullage volume, V(U).

8. A method according to claim 1, further comprising calculating a net volume flow rate, Q(U_F), of ambient air into the fuel tank ullage, U, via its vent system due to changes in the ullage volume, V(U), as fuel, F, is removed from the fuel tank.

9. A method according to claim 8, wherein the increasing ullage volume rate, δ

V(U)/δ

t, is calculated based upon a mass flow rate of fuel, {dot over (m)}(F), being removed from the fuel tank.

10. A method according to claim 6, further comprising calculating a net volume flow rate, Q(U_F), of ambient air into the fuel tank ullage, U, via its vent system due to changes in the ullage volume, V(U), as fuel, F, is removed from the fuel tank, and calculating a total volume flow rate, Q(U), of increasing ullage volume, U, where:

Q(U)=Q(U_P)+Q(U_F).

11. A method according to claim 10, further comprising calculating a mass flow rate, {dot over (m)}(U), of increasing fuel tank ullage based upon the volume flow rate Q(U) and the instantaneous ambient air pressure, P.

12. A method according to claim 1, wherein the mass flow rate of inerting gas {dot over (m)}(I) introduced into the aircraft fuel tank is actively controlled to be approximately equal to a mass flow rate, {dot over (m)}(U), of increasing fuel tank ullage.

13. A method according to claim 1, wherein the mass flow rate of inerting gas {dot over (m)}(I) introduced into the aircraft fuel tank is actively controlled to be greater than a mass flow rate, {dot over (m)}(U), of increasing fuel tank ullage by a value, x, where x is less than 2 g/s, preferably less than 1 g/s, and more preferably less than 0.5 g/s.

14. A method according to claim 1, wherein the mass flow rate of inerting gas {dot over (m)}(I) introduced into the aircraft fuel tank is controlled by adjusting a valve.

15. A method according to claim 1, wherein the mass flow rate of inerting gas {dot over (m)}(I) introduced into the aircraft fuel tank is controlled by adjusting a rate of generation of the inerting gas.

16. An aircraft including a vented fuel tank, a supply of inerting gas for rendering inert the fuel tank ullage, and a controller for performing the method according to claim 1.

17. An aircraft according to claim 16, further comprising one or more main engines each having a full authority digital engine controller (FADEC) coupled to the inerting gas controller.

18. An aircraft according to claim 16, further comprising an air data system coupled to the inerting gas controller.

19. An aircraft according to claim 16, further comprising an on-board inert gas generator for generating the supply of inerting gas and coupled to the inerting gas controller.

20. An aircraft according to claim 16, further comprising a valve coupled between the supply of inerting gas and the fuel tank, the valve being coupled to the inerting gas controller and adapted to control a flow of inerting gas to the fuel tank.