Control logic for gas turbine engine fuel economy

Patent metadata

Field	Value
Publication number	US-11725595-B2
Application number	US-202217648857-A
Country	US
Kind code	B2
Filing date	Jan 25, 2022
Priority date	May 31, 2019
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

A method of operating an engine of a multi-engine aircraft includes sequentially operating the engine through a plurality of cycles, each cycle including a breathing-in phase followed by a breathing-out phase. The breathing-in phase includes: i) in response to a speed of a rotor of the engine being at a sub-idle threshold, opening variable guide vanes upstream a compressor and injecting fuel into the combustor to increase rotor speed to a pre-determined upper threshold, and then ii) in response to the rotor speed reaching the pre-determined upper threshold, reducing a supply rate of fuel into the combustor and substantially closing the variable guide vanes. The breathing-out phase includes maintaining the variable guide vanes closed at least until the speed drops from the pre-determined upper threshold to the pre-determined sub-idle threshold.

First claim

The invention claimed is:

1. A method of operating an engine of a multi-engine aircraft, comprising:
sequentially operating the engine through a plurality of cycles, a given cycle of the plurality of cycles including a breathing-in phase followed by a breathing-out phase,
the breathing-in phase including:
i) in response to a speed of a rotor of the engine being at a sub-idle threshold, opening a set of variable guide vanes upstream an air compressor section of the engine and injecting a fuel into a combustor of the engine to increase the speed to at least approximately a pre-determined upper threshold, and then
ii) in response to the speed reaching the pre-determined upper threshold, at least reducing a supply rate of the fuel into the combustor and at least substantially closing the set of variable guide vanes,

the breathing-out phase including maintaining the set of variable guide vanes closed at least until the speed drops from the pre-determined upper threshold to at least approximately the pre-determined sub-idle threshold.

2. The method of claim 1 , wherein in the breathing-in phase of at least one repeating cycle of the plurality of cycles, the at least reducing the rate starts before a start of the closing the set of variable guide vanes.

3. The method of claim 1 , wherein in the breathing-in phase of at least one repeating cycle of the plurality of cycles, the opening the set of variable guide vanes starts at least approximately simultaneously with the injecting the fuel, and the injecting the fuel includes increasing the supply rate of the fuel into the combustor.

4. The method of claim 1 , wherein the at least reducing the rate includes reducing the rate to a zero supply rate.

5. The method of claim 1 , wherein the step of injecting the fuel into the combustor of the engine comprises spiking the supply rate of fuel flow into the combustor, the spiking and the opening of the set of variable guide vanes being timed to increase the speed of the rotor to the pre-determined upper threshold.

6. The method of claim 5 , wherein the spiking the supply rate includes increasing the rate is to an upper supply rate, followed by decreasing the rate to a lower supply rate, the upper supply rate being lower than a minimum fuel supply rate required for the engine to provide motive power to the multi-engine aircraft and greater than a substantially constant idle fuel supply rate required to maintain rotation of the rotor at a substantially constant idle rotation speed of the engine, the lower supply rate being lower than the upper supply rate, and wherein the opening the set of variable guide vanes is followed substantially immediately by the substantially closing the set of variable guide vanes.

7. The method of claim 1 , further comprising monitoring the speed of the rotor, and in response to the speed of the rotor decreasing to the pre-determined sub-idle threshold during the breathing-out phase of the given cycle, terminating the breathing-out phase of the given cycle and starting the breathing-in phase of a sequentially next cycle of the plurality of cycles.

8. The method of claim 7 , wherein during the breathing-in phase of the sequentially next cycle, injecting the fuel starts substantially immediately after the speed of the rotor reaches the pre-determined upper threshold during the breathing-out phase of the given cycle.

9. The method of claim 7 , wherein during the breathing-in phase of the sequentially next cycle, opening the set of variable guide vanes starts at one of: i) a substantially same time as a start of injecting the fuel, and ii) a pre-determined time after the start of injecting the fuel.

10. A multi-engine aircraft, comprising:
a first engine operable to provide motive power to the aircraft;
a second engine operable to provide motive power to the aircraft;
at least one controller operatively connected to the first engine and the second engines and configured to operate the first engine in a sub-idle mode while operating the second engine in an active mode, the sub-idle mode including sequentially executing a plurality of cycles, a given cycle of the plurality of cycles including a breathing-in phase followed by a breathing-out phase,
the breathing-in phase including: i) modulating a set of variable guide vanes upstream an air compressor section of the first engine to an open position, and modulating a fuel supply to a combustor of the first engine to an upper supply rate to increase a speed of a rotor of the first engine to an upper speed threshold, followed by ii) modulating the set of variable guide vanes to a substantially closed position, and modulating the fuel supply to a lower supply rate that is lower than the upper supply rate, in response to the speed of the rotor of the first engine reaching the upper speed threshold, and
the breathing-out phase including maintaining the set of variable guide vanes closed.

11. The aircraft of claim 10 , wherein the at least one controller is configured to start the modulating of the fuel supply to the lower supply rate substantially immediately after terminating the modulating the fuel supply to the upper supply rate, and to start the modulating the set of variable guide vanes to the closed position substantially immediately after terminating the modulating the set of variable guide vanes to the open position.

12. The aircraft of claim 10 , wherein the at least one controller is configured to switch operation of the first engine from the sub-idle mode into an active mode of the first engine at any point in time during operation of the first engine in the sub-idle mode.

13. The aircraft of claim 10 , wherein the modulating the fuel supply to the lower supply rate followed by modulating the fuel supply to the upper supply rate is part of spiking the fuel supply to the combustor of the first engine.

14. The aircraft of claim 13 , wherein the at least one controller is configured to start the spiking at least substantially simultaneously with starting the modulating the set of variable guide vanes to the open position, and to terminate the spiking at least substantially simultaneously with terminating the modulating the set of variable guide vanes to the closed position.

15. The aircraft of claim 10 , wherein the breathing-out phase includes maintaining the set of variable guide vanes closed at least until the speed of the rotor drops from the upper speed threshold to a sub-idle speed threshold.

Assignees

• Pratt & Whitney Canada

Inventors

• Coutu Daniel

Classifications

• F02C9/42 Primary

  specially adapted for the control of two or more plants simultaneously · CPC title

• F01D9/041

  using blades (F01D5/148 takes precedence) · CPC title

• F01D17/06

  responsive to speed · CPC title

• F01D17/16

  by means of nozzle vanes · CPC title

• F02C9/54

  by throttling the working fluid, by adjusting vanes · CPC title