Methods and systems for direct fuel quantity measurement

Patent metadata

Field	Value
Publication number	US-10060781-B2
Application number	US-201514818701-A
Country	US
Kind code	B2
Filing date	Aug 5, 2015
Priority date	Aug 5, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A method for fuel quantity gauging that measures the quantity of liquid fuel in a fuel tank. The method includes the following steps performed while fuel is flowing out of the fuel tank: changing a volume of gas in the fuel tank (e.g., by injecting or venting gas) during a time interval; measuring a rate of change of the volume of gas in the fuel tank during the time interval; measuring a rate of flow of fuel out of the fuel tank during the time interval; measuring a first pressure and a first temperature of the gas in the fuel tank at the start of the time interval; measuring a second pressure and a second temperature of the gas in the fuel tank at the end of the time interval; and calculating a quantity of fuel in the fuel tank based on the acquired measurement data.

First claim

The invention claimed is:

1. A system for measuring a quantity of liquid fuel in a fuel tank, comprising:
a first meter that measures a rate of flow of gas through a gas line that is in fluid communication with the fuel tank;
a second meter that measures a rate of flow of fuel out of the fuel tank via a fuel line;
a first gauge that measures an ullage temperature in an ullage of the fuel tank;
a second gauge that measures an ullage pressure in the ullage of the fuel tank; and
a processing unit programmed to calculate a quantity of fuel in the fuel tank based on measurement data from said first and second meters and from said first and second gauges.

2. The system as recited in claim 1 , further comprising a fuel gauge connected to receive and display symbology representing said quantity of fuel.

3. The system as recited in claim 1 , wherein said processing unit is programmed to calculate a quantity of fuel in the fuel tank at a second time subsequent to a first time based in part on respective ullage temperature and pressure measurements taken by said first and second gauges at said first and second times.

4. The system as recited in claim 1 , wherein said processing unit is programmed to:
calculate a change in mass of gas in the fuel tank by integrating an output of said first meter over a time interval from a first time to a second time;
calculate a change in volume of fuel in the fuel tank by integrating an output of said second meter over said time interval; and
calculate a quantity of fuel in the fuel tank at said second time based on the calculated changes in mass of gas and fuel in the fuel tank during said time interval and respective ullage temperature and pressure measurements taken by said first and second gauges at said first and second times.

5. The system as recited in claim 1 , wherein said processing unit is further programmed to cause said gas line to be closed in response to an ullage pressure that equals a preset maximum pressure.

6. The system as recited in claim 1 , wherein said gas line is connected to an on-board inert gas generation system.

7. The system as recited in claim 1 , wherein said gas line receives engine bleed air.

8. The system as recited in claim 1 , wherein said gas line is a vent.

9. The system as recited in claim 1 , wherein the fuel tank is part of an aircraft.

10. A method for measuring a quantity of liquid fuel in a fuel tank while fuel is flowing out of the fuel tank, comprising:
(a) changing a volume of gas in an ullage above the liquid fuel in the fuel tank during a time interval that starts at a first time and ends at a second time;
(b) measuring a rate of change of the volume of gas in the fuel tank during said time interval;
(c) measuring a rate of flow of fuel out of the fuel tank during said time interval;
(d) measuring a first pressure of gas in the fuel tank at said first time;
(e) measuring a first temperature of gas in the fuel tank at said first time;
(f) measuring a second pressure of gas in the fuel tank at said second time;
(g) measuring a second temperature of gas in the fuel tank at said second time; and
(h) calculating a quantity of fuel in the fuel tank based on measurement data acquired in steps (b) through (g),
wherein step (h) is performed by a processing unit.

11. The method as recited in claim 10 , further comprising closing a vent in fluid communication with the ullage prior to step (a), wherein step (a) comprises injecting gas into the fuel tank via a gas line during said time interval while the vent is closed, and step (b) comprises measuring a rate of flow of gas into the fuel tank via the gas line.

12. The method as recited in claim 11 , further comprising closing the gas line in response to an ullage pressure that equals a preset maximum pressure.

13. The method as recited in claim 10 , further comprising opening a vent in fluid communication with the ullage prior to step (a), wherein step (a) comprises venting gas out of the ullage via the open vent during said time interval, and step (b) comprises measuring a rate of flow of gas out of the ullage via the open vent.

14. The method as recited in claim 13 , further comprising closing said vent in response to an ullage pressure that equals zero.

15. The method as recited in claim 10 , further comprising displaying symbology representing said quantity of fuel.

16. The method as recited in claim 10 , wherein step (h) comprises:
calculating a change in mass of gas in the fuel tank during said time interval;
calculating a change in volume of fuel in the fuel tank during said time interval; and
calculating the quantity of fuel in the fuel tank at said second time based on the calculated changes in mass of gas and fuel in the fuel tank during said time interval and said first and second temperatures and said first and second pressures.

17. The method as recited in claim 10 , wherein said injected gas is nitrogen-enriched air.

18. The method as recited in claim 10 , wherein said injected gas is engine bleed air.

19. The method as recited in claim 10 , wherein steps (a) through (h) are performed onboard an aircraft.

20. A method for measuring a quantity of liquid fuel in a fuel tank onboard an aircraft during flight, comprising:
(a) changing a volume of gas in an ullage above the liquid fuel in the fuel tank during a time interval that starts at a first time and ends at a second time;
(b) measuring a rate of change of the volume of gas in the fuel tank during said time interval;
(c) measuring a rate of flow of fuel out of the fuel tank during said time interval;
(d) measuring a first pressure and a first temperature of gas in the fuel tank at said first time;
(e) measuring a second pressure and second temperature of gas in the fuel tank at said second time;
(f) calculating a change in mass of gas in the fuel tank during said time interval;
(g) calculating a change in volume of fuel in the fuel tank during said time interval;
(h) calculating the quantity of fuel in the fuel tank at said second time based on the calculated changes in mass of gas and volume of fuel in the fuel tank during said time interval, said first and second temperatures, and said first and second pressures; and
(i) displaying symbology representing said quantity of fuel,
wherein steps (f) through (h) are performed by a processing unit.

21. The system as recited in claim 3 , wherein said processing unit is programmed to calculate a quantity of fuel in the fuel tank using an equation representing an ideal gas law when the gas is an ideal gas or using a Van Der Waals equation when the gas is a Van Der Waals gas.

22. The system as recited in claim 10 , wherein during operation (h) said processing unit uses an equation representing an ideal gas law when the gas is an ideal gas or uses a Van Der Waals equation when the gas is a Van Der Waals.

23. The system as recited in claim 20 , wherein during operation (h) said processing unit uses an equation representing an ideal gas law when the gas is an ideal gas or uses a Van Der Waals equation when the gas is a Van Der Waals.

Assignees

• Boeing Co

Inventors

• Nguyen Sang H
• Kwok David W
• Smith David M

Classifications

• G01F23/14 Primary

  by measurement of pressure · CPC title

• G01F22/02

  involving measurement of pressure · CPC title

• G01F22/00 Primary

  Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for · CPC title

• G01F9/00

  Measuring volume flow relative to another variable, e.g. of liquid fuel for an engine · CPC title

• G01F23/0076 Primary

  Physics · mapped topic